v3.26.1
Investment Risks
Dec. 31, 2025
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such
sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Advantage Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Healthcare Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Healthcare Sector Risk. The profitability of companies in the healthcare sector may be adversely affected by, among other things, extensive government regulation, restrictions on government reimbursement for medical expenses, rising costs of medical products and services, pricing pressure, costs associated with obtaining and protecting patents, product liability and other claims, an increased emphasis on outpatient services, changes in the demand for medical products and services, a limited number of products, industry innovation, changes in technologies and other market, economic and public health developments. To the extent that the Fund concentrates its investments in one or more individual industries comprising the healthcare sector (such as, but not limited to, biotechnology, pharmaceuticals, medical equipment and supplies, healthcare technology, healthcare providers and services, and life sciences tools and services companies), the Fund will be particularly susceptible to the risks associated with such industry or industries, which may include the risks described above as well as other risks specific to such industry or industries.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely
affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Portfolio Turnover [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when
equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | ETFs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
ETFs. Shares of ETFs have many of the same risks as direct investments in common stocks or bonds and their market value may differ from their NAV because the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying securities. As a shareholder in an ETF, the Fund would bear its ratable share of that entity’s expenses while continuing to pay its own investment management fees and other expenses. As a result, the Fund and its shareholders will, in effect, be absorbing fees at two levels. Furthermore, disruptions in the markets for the securities underlying ETFs purchased or sold by the Fund could result in losses on the Fund’s investment in ETFs.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments,
significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Global Endurance Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities
(in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Global Insight Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Industrials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Portfolio Turnover [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its
portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Global Permanence Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may
reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Growth Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Small Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small Cap Companies. Investments in small cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Healthcare Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Healthcare Sector Risk. The profitability of companies in the healthcare sector may be adversely affected by, among other things, extensive government regulation, restrictions on government reimbursement for medical expenses, rising costs of medical products and services, pricing pressure, costs associated with obtaining and protecting patents, product liability and other claims, an increased emphasis on outpatient services, changes in the demand for medical products and services, a limited number of products, industry innovation, changes in technologies and other market, economic and public health developments. To the extent that the Fund concentrates its investments in one or more individual industries comprising the
healthcare sector (such as, but not limited to, biotechnology, pharmaceuticals, medical equipment and supplies, healthcare technology, healthcare providers and services, and life sciences tools and services companies), the Fund will be particularly susceptible to the risks associated with such industry or industries, which may include the risks described above as well as other risks specific to such industry or industries.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Portfolio Turnover [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its
portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Inception Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Industrials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Portfolio Turnover [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Portfolio Turnover. Consistent with its investment policies, the Fund will purchase and sell securities without regard to the effect on portfolio turnover. Higher portfolio turnover will cause the Fund to incur additional transaction costs.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign
issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and
pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Permanence Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Preferred Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Preferred Securities. Preferred securities have many of the characteristics of and are subject to many of the risks associated with both fixed-income securities and equity securities. Preferred securities may pay fixed or adjustable rates of return. As with fixed-income securities, the market value of preferred securities is sensitive to changes in interest rates. Preferred securities generally decrease in value if interest rates rise and increase in value if interest rates fall. In addition, preferred securities are also subject to risks applicable generally to equity securities, such as issuer-specific and market risks. A company’s preferred securities generally pay dividends only after the company makes required payments to
holders of its bonds and other debt, so the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | ETFs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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ETFs. Shares of ETFs have many of the same risks as direct investments in common stocks or bonds and their market value may differ from their NAV because the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying securities. As a shareholder in an ETF, the Fund would bear its ratable share of that entity’s expenses while continuing to pay its own investment management fees and other expenses. As a result, the Fund and its shareholders will, in effect, be absorbing fees at two levels. Furthermore, disruptions in the markets for the securities underlying ETFs purchased or sold by the Fund could result in losses on the Fund’s investment in ETFs.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Healthcare Concentration Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Healthcare Concentration Risk. The Fund will concentrate its investments in the group of industries comprising the healthcare sector and, from time to time, may concentrate its investments in one or more individual industries in the group of industries comprising the healthcare sector. By concentrating its investments in the group of industries comprising the healthcare sector, the Fund has greater exposure to the potential adverse economic, regulatory, political and other changes affecting companies operating within such sector. The profitability of companies in the healthcare sector may be adversely affected by, among other things, extensive government regulation, restrictions on government reimbursement for medical expenses, rising costs of medical products and services, pricing pressure, costs associated with obtaining and protecting patents, product liability and other claims, an increased emphasis on outpatient services, changes in the demand for medical products and services, a limited number of products, industry innovation, changes in technologies and other market, economic and public health developments. To the extent that the Fund concentrates its investments in one or more individual industries comprising the healthcare sector (such as, but not limited to, biotechnology, pharmaceuticals, medical equipment and supplies, healthcare technology, healthcare providers and services, and life sciences tools and services companies), the Fund will be particularly susceptible to the risks associated with such industry or industries.
 
Biotechnology, healthcare technology, pharmaceutical and life sciences tools and services companies are heavily dependent on patents and intellectual property rights and the loss or impairment of such rights will negatively impact a company’s profitability. In addition, these companies are subject to the risk of new technologies and competition, large expenditures on research and development of products and services that may not prove commercially successful, regulations and restrictions imposed by the Food and Drug Administration, the Environmental Protection Agency, state and local governments and foreign regulatory authorities, and thin capitalization. Medical equipment and supply companies are heavily dependent on patent protection and may be subject to extensive litigation based on product liability and similar claims. In addition, medical equipment companies are subject to the risk that products can become obsolete due to industry innovation, changes in technology or other market developments, and may not receive necessary regulatory approvals to become commercially viable. Healthcare providers and services companies are particularly subject to certain risks, including restrictions on government reimbursement for medical expenses, an increased emphasis on outpatient services, rising costs of medical products and public health conditions.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | IPOs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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IPOs. The Fund may purchase shares issued as part of, or a short period after, a company’s IPO, and may at times dispose of those shares shortly after their acquisition. The Fund’s purchase of shares issued in IPOs exposes it to the risks associated with companies that have little operating history as public companies. The market for IPO issuers may be volatile, and share prices of newly-public companies have fluctuated significantly over short periods of time. IPOs may produce high, double-digit returns. Such returns are highly unusual and may not be sustainable.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | SPACs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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SPACs. A SPAC  is a publicly traded company that raises investment capital for the purpose of acquiring or merging with an existing company. An investment in a SPAC is subject to the risks that any proposed acquisition or merger may not obtain the requisite approval of SPAC shareholders, may require governmental or other approvals that it fails to obtain or that an acquisition or merger, once effected, may prove unsuccessful and lose value. In addition, among other conflicts of interest, the economic interests of the management, directors, officers and related parties of a SPAC can differ from the economic interests of public shareholders, which may lead to conflicts as they evaluate, negotiate and recommend business combination transactions to shareholders. An investment in a SPAC is also subject to the risk that a significant portion of the funds raised by the SPAC may be expended during the search for a target acquisition or merger.  
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or
other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable.  Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Counterpoint Global Portfolios) | Vitality Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector,  the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or
liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Asia Market [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Asia Market. The small size of securities markets and the low trading volume in many countries in Asia may lead to a lack of liquidity. The share prices of companies in the region tend to be volatile and there is a significant possibility of loss. Many of the countries in the region are developing, both politically and economically, and as a result companies in the region may be subject to risks like nationalization or other forms of government interference, and/or may be heavily reliant on only a few industries or commodities. Investments in the region may also be subject to currency risks, such as restrictions on the flow of money in and out of the country, extreme volatility relative to the U.S. dollar and devaluation, all of which could decrease the value of the Fund. Some countries in the region have previously experienced currency devaluations that resulted in higher interest rates, reductions in economic activity and drops in securities prices. In addition, because the Fund concentrates in a single region of the world, the Fund’s performance may be more volatile than that of a fund that invests globally. Consequently, if Asian securities fall out of favor, it may cause the Fund to underperform funds that do not concentrate in a single region of the world.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese
central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE
structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Opportunity Portfolios) | Asia Opportunity Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector,  the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is
forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Frontier Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Frontier Emerging Market Securities. Investing in the securities of issuers operating in frontier emerging markets involves a high degree of risk and special considerations not typically associated with investing in the securities of other foreign or U.S. issuers. In addition, the risks associated with investing in the securities of issuers operating in emerging market countries are magnified when investing in frontier emerging market countries. These types of investments could be affected by factors not usually associated with investments in U.S. issuers, including risks associated with expropriation and/or nationalization, political or social instability, pervasiveness of corruption and crime, armed conflict, the impact on the economy of civil war, religious or ethnic unrest and the withdrawal or non-renewal of any license enabling the Fund to trade in securities of a particular country, confiscatory taxation, restrictions on transfers of assets, lack of uniform accounting, auditing and financial reporting standards, less publicly available financial and other information, less stringent investor protections and disclosure standards, diplomatic development which could affect U.S. investments in those countries and potential difficulties in enforcing contractual obligations. These risks and special considerations make investments in companies operating in frontier emerging market countries highly speculative in nature and, accordingly, an investment in
the Fund must be viewed as highly speculative in nature and may not be suitable for an investor who is not able to afford the loss of his or her entire investment. To the extent that the Fund invests a significant percentage of its assets in a single frontier emerging market country, the Fund will be subject to heightened risk associated with investing in frontier emerging market countries and additional risks associated with that particular country. A government of a frontier emerging market country may limit or cause delay in the convertibility or repatriation of its currency and therefore could adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. From time to time, certain of the companies in which the Fund expects to invest may operate in, or have dealings with, countries subject to sanctions or embargoes imposed by the U.S. Government and the United Nations and/or countries identified by the U.S. Government as state sponsors of terrorism. A company may suffer damage to its reputation if it is identified as such a company and, as an investor in such companies, the Fund will be indirectly subject to those risks. Certain frontier market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in frontier markets countries. In addition, a substantial portion of the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar governmental actions could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities or groups of securities, and thus may make the Fund’s investments in such securities less liquid or more difficult to value. In addition, as a result of economic sanctions, the Fund may be forced to sell or otherwise dispose of investments at inopportune times or prices.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct
ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Opportunity Portfolios) | Developing Opportunity Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector,  the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require
holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and
 
South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios) | Global Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to
obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector,  the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the
largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives
and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios) | International Advantage Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector,  the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its
portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect
on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding
company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Opportunity Portfolios) | International Opportunity Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types
 
of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Preferred Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Preferred Securities. Preferred securities have many of the characteristics of and are subject to many of the risks associated with both fixed-income securities and equity securities. Preferred securities may pay fixed or adjustable rates of return. As with fixed-income securities, the market value of preferred securities is sensitive to changes in interest rates. Preferred securities generally decrease in value if interest rates rise and increase in value if interest rates fall. In addition, preferred securities are also subject to risks applicable generally to equity securities, such as issuer-specific and market risks. A company’s preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt, so the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | ETFs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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ETFs. Shares of ETFs have many of the same risks as direct investments in common stocks or bonds and their market value may differ from their NAV because the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying securities. As a shareholder in an ETF, the Fund would bear its ratable share of that entity’s expenses while continuing to pay its own investment management fees and other expenses. As a result, the Fund and its shareholders will, in effect, be absorbing fees at two levels. Furthermore, disruptions in the markets for the securities underlying ETFs purchased or sold by the Fund could result in losses on the Fund’s investment in ETFs.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), economic and market risks, and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments,
significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Applied Equity Portfolios) | Global Concentrated Portfolio | Non-Diversification [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the
 
Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Preferred Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Preferred Securities. Preferred securities have many of the characteristics of and are subject to many of the risks associated with both fixed-income securities and equity securities. Preferred securities may pay fixed or adjustable rates of return. As with fixed-income securities, the market value of preferred securities is sensitive to changes in interest rates. Preferred securities generally decrease in value if interest rates rise and increase in value if interest rates fall. In addition, preferred securities are also subject to risks applicable generally to equity securities, such as issuer-specific and market risks. A company’s preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt, so the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | ETFs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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ETFs. Shares of ETFs have many of the same risks as direct investments in common stocks or bonds and their market value may differ from their NAV because the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying securities. As a shareholder in an ETF, the Fund would bear its ratable share of that entity’s expenses while continuing to pay its own investment management fees and other expenses. As a result, the Fund and its shareholders will, in effect, be absorbing fees at two levels. Furthermore, disruptions in the markets for the securities underlying ETFs purchased or sold by the Fund could result in losses on the Fund’s investment in ETFs.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), economic and market risks, and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such
companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●


Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Applied Equity Portfolios) | Global Core Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when
equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Preferred Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Preferred Securities. Preferred securities have many of the characteristics of and are subject to many of the risks associated with both fixed-income securities and equity securities. Preferred securities may pay fixed or adjustable rates of return. As with fixed-income securities, the market value of preferred securities is sensitive to changes in interest rates. Preferred securities generally decrease in value if interest rates rise and increase in value if interest rates fall. In addition, preferred securities are also subject to risks applicable generally to equity securities, such as issuer-specific and market risks. A company’s preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt, so the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | ETFs [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
ETFs. Shares of ETFs have many of the same risks as direct investments in common stocks or bonds and their market value may differ from their NAV because the supply and demand in the market for ETF shares at any point in time is not always identical to the supply and demand in the market for the underlying securities. As a shareholder in an ETF, the Fund would bear its ratable share of that entity’s expenses while continuing to pay its own investment management fees and other expenses. As a result, the Fund and its shareholders will, in effect, be absorbing fees at two levels. Furthermore, disruptions in the markets for the securities underlying ETFs purchased or sold by the Fund could result in losses on the Fund’s investment in ETFs.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●


Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors,
asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Applied Equity Portfolios) | US Core Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely
affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Private Placements and Restricted Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Private Placements and Restricted Securities. The Fund’s investments may include privately placed and restricted securities, which are generally subject to resale or transfer restrictions or prohibitions. Private placements and restricted securities may not be listed on an exchange and may have no active trading market. The Fund may be unable to dispose of privately placed and restricted securities promptly or may be able to sell privately placed and restricted securities only at disadvantageous times or prices, especially under adverse market or economic conditions or in the event of adverse changes in the financial condition of the issuer. There is no assurance that a liquid market will exist for privately placed and restricted securities and these securities could have the effect of increasing the level of Fund illiquidity. In addition, the market for certain investments deemed liquid at the time of purchase may become illiquid under adverse market or economic conditions. Restricted securities, including privately placed securities, may be difficult to value and may experience significant price volatility, and there is typically less information available about issuers of private placements and restricted securities and there is no assurance that the information obtained by the Adviser is reliable. Private placements and restricted securities may involve a high degree of business and financial risk and may result in substantial losses to the Fund.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing  interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on
foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the  U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Growth Portfolio - Class IR) | Growth Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely
affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets
has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the  U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the  U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or  inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain
 
transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios - Class IR) | Global Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector. Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military, or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Focused Investing [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Focused Investing. Although the Fund is a diversified investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund typically invests a significant portion of its portfolio in a limited number of issuers, which may be in the
same industry, sector or geographic region. As a result, the Fund will be more susceptible to risks associated with, and negative events affecting those issuers, industries, sectors or geographic regions, and a decline in the value of a particular instrument may cause the Fund’s overall value to be more volatile and decline to a greater degree than if the Fund were invested more widely.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the  U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the  U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or  inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized
 
by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Opportunity Portfolios - Class IR) | International Opportunity Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities.  U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions  affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), economic and market risks, and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities
(in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than
investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Passport Overseas Equity Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector(s). Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Industrials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities.  U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions  affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price
will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), economic and market risks, and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent
requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the  U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which
certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the  U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or  inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese
government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Leaders Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information
technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities.  U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions  affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks such as currency, political (including geopolitical), economic and market risks, and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been,
imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss. Investments in currency derivatives may substantially change the Fund’s exposure to currency exchange rates and could result in losses to the Fund if currencies do not perform as the Adviser expects. Foreign currency forward exchange contracts and currency futures and options contracts create exposure to currencies in which the Fund’s securities are not denominated.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have
heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Classes I, A, L, C and R6) | Emerging Markets Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions.  During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the  Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or
other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a  counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the  counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt
or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Passport Overseas Equity Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Consumer Discretionary Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Consumer Discretionary Sector Risk. To the extent that the Fund invests a substantial portion of its assets in the consumer discretionary sector, the Fund will be particularly susceptible to the risks associated with companies operating in such sector(s). Companies in the consumer discretionary sector are subject to risks, including fluctuations in the performance of the overall domestic and international economy, shipment and supply chain disruptions, interest rate changes, currency exchange rates, increased competition and consumer confidence. Performance of such companies may also be adversely affected by factors such as reduced disposable household income, reduced consumer spending, and changing demographics and consumer tastes.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Industrials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a  counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block] China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the  U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the  U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block] Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Leaders Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency
exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets
has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a  counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates. Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss. Investments in currency derivatives may substantially change the Fund’s exposure to currency exchange rates and could result in losses to the Fund if currencies do not perform as the Adviser expects. Foreign currency forward exchange contracts and currency futures and options contracts create exposure to currencies in which the Fund’s securities are not denominated.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities. If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments,
adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | China Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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China Risk. Investments in securities of Chinese issuers involve risks associated with investments in foreign markets as well as special considerations not typically associated with investments in the U.S. markets or other foreign (including emerging) markets. For example, the Chinese government has historically exercised substantial control over virtually every sector of the Chinese economy through administrative regulation, state ownership and/or other involvement. Actions of the Chinese central and local government authorities continue to have a substantial effect on economic conditions in China and operations of particular Chinese companies. In addition, the Chinese government has actively intervened in Chinese companies’ operations and structures and taken (and may continue to take) actions that influenced the prices at which certain goods may be sold, encouraged companies to invest or concentrate in particular industries, induced mergers between companies in certain industries and induced private companies to publicly offer their securities. Investments in China involve risk of a total loss due to government action or inaction or other adverse circumstances.
 
Additionally, the Chinese economy is export-driven and highly reliant on trade. Adverse changes to the economic conditions, trading policies and taxation of imports of its primary trading partners, such as the United States, Japan and South Korea, would adversely impact the Chinese economy and the Fund’s investments. Moreover, a slowdown in other significant economies of the world, such as the United States, the European Union and certain Asian countries, may adversely affect economic growth or the value of investments in China. An economic downturn in China would adversely impact the Fund’s investments. In addition, certain securities are, or may in the future, become restricted and/or sanctioned by the U.S. government or other governments and the Fund may be forced to sell or unable to sell such securities and incur a loss as a result and the Fund may be unable to purchase securities of Chinese issuers from time to time.
 
U.S. relations with China are strained, because of, among other things, a series of trade, international treaty, tax, and sanctions actions taken by the United States and China against each other, including the designation of China as a “foreign adversary” of the U.S., as well as countersanctions or countermeasures from the Chinese government that have been triggered or are expected to be triggered. Moreover, recent developments in relations between the U.S., other trading partners and China have heightened concerns (and the realization) of increased tariffs and restrictions on trade between the two countries, such as the potential for an escalation in trade tensions or a trade war. Increases in tariffs or trade restrictions (and threats thereof) could lead to a significant reduction in international trade, which could have a negative impact on China’s export industry, Chinese issuers, the liquidity or price of the Fund’s direct or indirect investments in China and, therefore, the Fund’s investments.
 
These and other developments, including government actions or inactions, would likely result in significant illiquidity risk or losses or forced disposition for Chinese investments. The Chinese securities markets are emerging markets characterized by a relatively small number of equity issues and relatively low trading volume, resulting in decreased liquidity, greater price volatility (caused by, among other things, military, diplomatic, or trade conflicts and government intervention in economic and securities markets), and potentially fewer investment opportunities for the Fund. The Fund’s investments in Chinese securities are also subject to additional risks associated with differing regulatory and audit requirements in the Chinese securities market as compared to the U.S. securities market, including a lack of reliable audits and other financial information regarding many Chinese companies and heightened risk of market manipulation and fraud, which may be increased through actions taken by the Chinese government. In addition, the relationship between China and Taiwan is particularly sensitive, and hostilities between China and Taiwan, including continued threats by China to invade and control Taiwan, present a significant risk to the Fund’s investments in China. Ongoing political tension between the People’s Republic of China and the Hong Kong Special Administrative Region may have impacts on the economy of Hong Kong, and these impacts remain uncertain.
 
Risks of Investing through Stock Connect. The Fund may invest in A-shares listed and traded through Stock Connect, or on such other stock exchanges in China which participate in Stock Connect from time to time or in the future. Trading through Stock Connect is subject to a number of restrictions that may affect the Fund’s investments and returns. Moreover, Stock Connect A-shares generally may not be sold, purchased or otherwise transferred other than through Stock Connect in accordance with applicable rules. The Stock Connect program is a relatively new program and may be subject to further interpretation and guidance. There can be no assurance as to the program’s continued existence or whether future developments regarding the program may restrict or adversely affect the Fund’s investments or returns. Because certain transactions through Stock Connect may not be subject to certain investor protection programs, the Fund may be exposed to the risks of default of the broker(s) they engage in their trading in China A Shares.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Variable Interest Entities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Variable Interest Entities. Chinese operating companies sometimes rely on variable interest entity (“VIE”) structures to raise capital from non-Chinese investors because of Chinese government limitations or prohibitions on direct foreign ownership in certain industries. In a VIE structure, a series of contractual arrangements are entered into between a holding company domiciled outside of China and a Chinese operating company or companies, which are intended to mimic direct
ownership in the operating company, but in many cases these arrangements have not been tested in court and it is not clear that the contracts are enforceable or that the structures will otherwise work as intended. The offshore holding company, which is not a Chinese operating company, then issues exchange-traded shares that are sold to the public, including non-Chinese investors (such as the Fund). In addition to the risks generally associated with investing in China and a Chinese operating company, the shares of the holding company purchased by the Fund would not be equity ownership interests in the Chinese operating company and the Fund’s interest would be subject to substantial legal, operational and other risks associated with the company’s use of the VIE structure. For example, the Chinese government has not approved VIE structures and at any time without advance notice the Chinese government or a Chinese regulator or court could determine that the contractual arrangements constituting part of the VIE structure are unenforceable or do not comply with applicable law or regulations, these laws or regulations could change or be interpreted differently in the future, and the Chinese government also may with no advance notice otherwise intervene in or exert influence over VIE structures or the related Chinese operating companies. If any of these or similar risks or developments materialize, the Fund’s investment in the holding company may suddenly and significantly decline in value or become worthless because of, among other things, difficulty enforcing (or the inability to enforce) the contractual arrangements or materially adverse effects on the Chinese operating company’s performance. In these circumstances, the Fund could experience significant or total losses with no recourse available. From time to time, the Fund’s investments in  U.S.-listed shell companies relying on VIE structures to obtain exposure to Chinese operating companies could be significant. A decline or worsening in diplomatic or other relations between the U.S. and China could increase the risks associated with the VIE structure.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | India Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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India Risk. To the extent that the Fund invests a substantial portion of its assets in Indian issuers, the value of the Fund’s assets may be adversely affected by political, economic, social and religious factors impacting Indian businesses and the Indian economy, changes in Indian law or regulations and the status of India’s relations with other countries. Indian government actions in the future could have a significant effect on the Indian economy, which could affect private sector companies and the Fund, market conditions, and prices and yields of securities in the Fund’s portfolio. To the extent the Fund invests a significant portion of its assets in Indian businesses and the Indian economy, factors that have an adverse impact on Indian businesses and the Indian economy may have a disproportionate impact on the Fund’s performance.
(MSIF - Emerging Markets Equity Portfolios - Class IR) | Emerging Markets Portfolio | Foreign Currency [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency. The Fund’s investments in foreign securities may be denominated in foreign currencies. The value of foreign currencies may fluctuate relative to the value of the U.S. dollar. Since the Fund may invest in such non-U.S. dollar-denominated securities, and therefore may convert the value of such securities into U.S. dollars, changes in currency exchange rates can increase or decrease the U.S. dollar value of the Fund’s assets. Currency exchange rates may fluctuate significantly over short periods of time for a number of reasons, including changes in interest rates and the overall economic health of the issuer. Devaluation of a currency by a country’s government or banking authority also will have a significant impact on the value of any investments denominated in that currency. The Adviser may use derivatives to seek to reduce this risk. The Adviser may in its discretion choose not to hedge against currency risk. In addition, certain market conditions may make it impossible or uneconomical to hedge against currency risk.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities
(in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivatives transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Non-Diversification [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that
issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | Global Franchise Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Global Franchise Companies.  Changes in the worldwide economy, consumer spending, competition, demographics and consumer preferences, government regulation and economic conditions may adversely affect global franchise companies and may negatively impact the Fund to a greater extent than if the Fund’s assets were invested in a wider variety of companies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Franchise Portfolio | ESG Investment Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●


ESG Investment Risk. To the extent that potentially financially material environmental, social and/or governance (“ESG”) issues are considered as an integrated component of the investment decision-making process, investment performance of the Fund may be impacted and may differ from similar strategies that do not consider such issues. The Adviser’s and/or Sub-Adviser’s ESG analysis may be subjective, may rely on limited data, and may change over time.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when
equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise
dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivative transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Financials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Financials Sector Risk. To the extent the Fund invests a substantial portion of its assets in the financials sector, factors that have an adverse impact on this sector may have a disproportionate impact on the Fund’s performance. The financials sector
can be affected by global and local economic conditions, such as the levels and liquidity of the global and local financial and asset markets, the absolute and relative level and volatility of interest rates and equity prices, investor sentiment, inflation, and the availability and cost of credit. Adverse developments in these conditions can have a greater adverse effect on the financials sector of an emerging market economy than on other industries of its economy. The enactment of new legislation or regulations, as well as changes in interpretation and enforcement of current laws, may affect the manner of operations and profitability of the financials sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | Non-Diversification [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | Global Stars Portfolio | ESG Investment Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●


ESG Investment Risk. To the extent that potentially financially material environmental, social and/or governance (“ESG”) issues are considered as an integrated component of the investment decision-making process, investment performance of the Fund may be impacted and may differ from similar strategies that do not consider such issues. The Adviser’s and/or Sub-Adviser’s ESG analysis may be subjective, may rely on limited data, and may change over time.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Information Technology Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and
competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Industrials Sector Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Equity Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Convertible Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Foreign and Emerging Market Securities [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the
largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Derivatives [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivatives transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Small and Mid Cap Companies [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Liquidity [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Market and Geopolitical Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | Active Management Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Equity Portfolio | ESG Investment Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
●
ESG Investment Risk. To the extent that potentially financially material environmental, social and/or governance (“ESG”) issues are considered as an integrated component of the investment decision-making process, investment performance of the Fund may be impacted and may differ from similar strategies that do not consider such issues. The Adviser’s and/or Sub-Adviser’s ESG analysis may be subjective, may rely on limited data, and may change over time.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] There is no assurance that the Fund will achieve its investment objective, and you can lose money investing in this Fund.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Risk Not Insured Depository Institution [Member]  
Prospectus [Line Items]  
Risk [Text Block] Shares of the Fund are not bank deposits and are not guaranteed or insured by the Federal Deposit Insurance Corporation or any other government agency.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Information Technology Sector Risk [Member]  
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Information Technology Sector Risk. To the extent the Fund invests a substantial portion of its assets in the information technology sector, the value of Fund shares may be particularly impacted by events that adversely affect the information technology sector, such as rapid changes in technology product cycles, product obsolescence, government regulation, and competition, and may fluctuate more than that of a fund that does not invest significantly in companies in the technology sector.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Industrials Sector Risk [Member]  
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Industrials Sector Risk. To the extent that the Fund invests significantly in the industrials sector, the Fund will be particularly susceptible to the risks associated with companies operating in this sector. For example, the value of securities issued by companies in the industrials sector may be adversely affected by changes in government regulations, domestic and world events and economic conditions. In addition, companies in the industrials sector may be adversely affected by, among other developments, environmental damages, product liability claims, commodity prices and exchange rates as well as changes in the supply of and demand for both their specific products or services and for industrials sector products in general.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Equity Securities [Member]  
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Equity Securities. In general, prices of equity securities are more volatile than those of fixed-income securities. U.S. and foreign stock markets, and equity securities of individual issuers, have experienced periods of substantial price volatility in the past and it is possible that they will do so again in the future. The prices of equity securities fluctuate, sometimes rapidly or widely, in response to activities specific to the issuer of the security as well as factors unrelated to the fundamental condition of the issuer, including general market, economic, political and public health conditions. During periods when
equity securities experience heightened volatility, such as during periods of market, economic or financial uncertainty or distress, the Fund’s investments in equity securities are subject to heightened risks.
 
The value of equity securities and related instruments decline in response to perceived or actual adverse changes in the economy, economic outlook or financial markets; deterioration in investor sentiment; inflation, interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer- and sector-specific considerations; unexpected trading activity among retail investors; and other factors. Market conditions affect certain types of equity securities to a greater extent than other types of equity securities. If the stock market declines, the value of the Fund’s equity securities will also likely decline, which will result in a decrease in the value of your investment in the Fund. Although prices can rebound, there is no assurance that prices of the Fund’s equity securities will return to previous levels.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Convertible Securities [Member]  
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Convertible Securities. A convertible security is a bond, debenture, note, preferred stock, right, warrant or other security that may be converted into or exchanged for a prescribed amount of common stock or other security of the same or a different issuer or into cash within a particular period of time at a specified price or formula. To the extent that the Fund invests in convertible securities, and the convertible security’s investment value is greater than its conversion value, its price will be likely to increase when interest rates fall and decrease when interest rates rise. If the conversion value exceeds the investment value, the price of the convertible security will tend to fluctuate directly with the price of the underlying security.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Foreign and Emerging Market Securities [Member]  
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Foreign and Emerging Market Securities. Investments in foreign markets entail special risks, such as currency, political (including geopolitical), economic and market risks and heightened risks, that may result in losses to the Fund. There also may be greater market volatility, less reliable financial information, less stringent investor protections and disclosure standards, higher transaction and custody costs and risks, decreased market liquidity and less government and exchange regulation associated with investments in foreign markets. In addition, investments in certain foreign markets that have historically been considered stable may become more volatile and subject to increased risk due to developments and changing conditions in such markets. Moreover, the growing interconnectivity of global economies and financial markets has increased the probability that adverse developments and conditions in one country or region will affect the stability of economies and financial markets in other countries or regions. Certain foreign markets may rely heavily on particular industries or foreign capital and are more vulnerable to diplomatic developments (including regional and global, military or other conflicts), the imposition of economic sanctions against a particular country or countries, organizations, companies, entities and/or individuals, changes in international trading patterns, trade barriers (including tariffs) and other protectionist or retaliatory measures. Investments in foreign markets may also be adversely affected by governmental interventions or other actions, such as the imposition of capital controls, nationalization of companies or industries, expropriation of assets or the imposition of punitive taxes. The governments of certain countries may prohibit or impose substantial restrictions on foreign investing in their capital markets or in certain sectors or industries. In addition, a foreign government may limit or cause delay in the convertibility or repatriation of its currency which would adversely affect the U.S. dollar value and/or liquidity of investments denominated in that currency. Certain foreign investments may become less liquid and decline in value in response to market developments or adverse investor perceptions, or become illiquid after purchase by the Fund, particularly during periods of market, economic, political and social turmoil. When the Fund holds illiquid investments, its portfolio may be harder to value. The risks of investing in emerging market countries are greater than the risks associated with investments in foreign developed countries. Certain emerging market countries may be subject to less stringent requirements regarding accounting, auditing, financial reporting and record keeping and therefore, material information related to an investment may not be available or reliable. Certain emerging market or developing countries are among the largest debtors to commercial banks and foreign governments. The issuer or governmental authority that controls the repayment of sovereign debt may not be willing or able to repay the principal and/or pay interest when due in accordance with the terms of such obligations. In addition, foreign governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling or additional lending to defaulting governments. Moreover, there is no bankruptcy proceeding by which defaulted sovereign debt may be collected in whole or in part. In addition, the Fund is limited in its ability to exercise its legal rights or enforce a counterparty’s legal obligations in certain jurisdictions outside of the United States, in particular, in emerging market countries. In addition, the Fund’s investments in foreign issuers may be denominated in foreign currencies and therefore, to the extent unhedged, the value of those investments will fluctuate with U.S. dollar exchange rates.  Economic sanctions or other similar measures may be, and have been, imposed against certain countries, organizations, companies, entities and/or individuals. Economic sanctions and other similar measures could, among other things, effectively restrict or eliminate the Fund’s ability to purchase or sell securities (in the sanctioned country and other markets), negatively impact the value or liquidity of  the Fund’s investments, significantly delay or prevent the settlement of the Fund’s securities transactions, force the Fund to sell or otherwise
dispose of investments at inopportune times or prices, or impair the Fund’s ability to meet its investment objective or invest in accordance with its investment strategies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Foreign Currency Forward Exchange Contracts [Member]  
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Foreign Currency Forward Exchange Contracts. To the extent the Fund seeks to hedge its foreign currency exposure by the use of foreign currency forward exchange contracts, the precise matching of the foreign currency forward exchange contract amounts and the value of the securities involved will not generally be possible because the future value of such securities in foreign currencies will change as a consequence of market movements in the value of those securities between the date on which the contract is entered into and the date it matures. There is additional risk that such transactions may reduce or preclude the opportunity for gain if the value of the currency should move in the direction opposite to the position taken and that foreign currency forward exchange contracts create exposure to currencies in which the Fund’s securities are not denominated. The use of foreign currency forward exchange contracts involves the risks associated with derivatives and the risk of loss from the insolvency or bankruptcy of the counterparty to the contract or the failure of the counterparty to make payments or otherwise comply with the terms of the contract.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Derivatives [Member]  
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Derivatives. Derivatives and other similar instruments that create synthetic exposure often are subject to risks similar to those of the underlying asset or instrument, including market risk, and may be subject to additional risks, including imperfect
correlation between the value of the derivative and the underlying asset, risks of default by the counterparty to certain transactions, magnification of losses incurred due to changes in the market value of the securities, instruments, indices or interest rates to which the derivative instrument relates, risks that the transactions may not be liquid, risks arising from margin and payment requirements, risks arising from mispricing or valuation complexity and operational and legal risks. Certain derivatives transactions may give rise to a form of leverage. Leverage magnifies the potential for gain and the risk of loss.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Small and Mid Cap Companies [Member]  
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Small and Mid Cap Companies. Investments in small and mid cap companies may involve greater risks than investments in larger, more established companies. The securities issued by small and mid cap companies may be less liquid and such companies may have more limited markets, financial resources and product lines, and may lack the depth of management of larger companies.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Liquidity [Member]  
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Liquidity. The Fund may make investments that are less liquid, illiquid or restricted or that may become illiquid or less liquid in response to overall economic conditions or adverse investor perceptions, and which may entail greater risk than investments in other types of securities. These investments may be more difficult to value or sell, particularly in times of market turmoil, and there may be little trading in the secondary market available for particular securities.  If the Fund is forced to sell an illiquid or restricted security to fund redemptions or for other cash needs, it may be forced to sell the security at a loss or for less than its fair value and may be unable to sell the security at all.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Market and Geopolitical Risk [Member]  
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Market and Geopolitical Risk. The value of your investment in the Fund is based on the values of the Fund’s investments, which change due to economic, geopolitical and other events that affect the U.S. and global markets generally, as well as those that affect or are perceived or expected to affect particular regions, countries, industries, companies, issuers, sectors, asset classes or governments. These types of events may be sudden and unexpected, and could adversely affect the value (or income generated by) and liquidity of the Fund’s investments, which may in turn impact the Fund’s ability to sell securities and/or its ability to meet redemptions. The risks associated with these developments may be magnified if certain social, political, economic and other conditions and events (such as war, natural disasters or events, epidemics and pandemics, terrorism, conflicts, social unrest, recessions, inflation, interest rate changes, supply chain disruptions and the threat and/or actual imposition of tariffs, trade barriers and other protectionist or retaliatory measures)  adversely interrupt or otherwise affect the global economy and financial markets. It is difficult to predict when events affecting the  U.S. or global financial markets or economies may occur, the effects that such events may have and the duration of those effects (which may last for extended periods). These types of events may negatively impact broad segments of businesses and populations and have a significant and rapid negative impact on the performance or value of the Fund’s investments, adversely affect and increase the volatility of the Fund’s share price and exacerbate pre-existing risks to the Fund. The frequency and magnitude of resulting changes in the value of the Fund’s investments cannot be predicted.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Active Management Risk [Member]  
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Active Management Risk. In pursuing the Fund’s investment objective, the Adviser has considerable leeway in deciding which investments to buy, hold or sell on a day-to-day basis, and which trading strategies to use. For example, the Adviser, in its discretion, may determine to use some permitted trading strategies while not using others. The success or failure of such decisions will affect the Fund’s performance.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | Non-Diversification [Member]  
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Non-Diversification. The Fund is non-diversified, which means that the Fund may invest a greater percentage of its assets in a smaller number of issuers than a diversified fund. Because the Fund is non-diversified, it may be more susceptible to an adverse event affecting a single issuer or portfolio investment than a diversified portfolio and a decline in the value of that issuer’s securities or that portfolio investment may cause the Fund’s overall value to decline to a greater degree than a diversified portfolio.
(MSIF - International Equity Portfolios - Classes I, A, L, C and R6) | International Resilience Portfolio | ESG Investment Risk [Member]  
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ESG Investment Risk. To the extent that potentially financially material environmental, social and/or governance (“ESG”) issues are considered as an integrated component of the investment decision-making process, investment performance of the Fund may be impacted and may differ from similar strategies that do not consider such issues. The Adviser’s and/or Sub-Adviser’s ESG analysis may be subjective, may rely on limited data, and may change over time.