Investment Strategy	Sep. 30, 2025
MSIFT Discovery Portfolio - Classes I, A, L, C and R6 \| Discovery Portfolio
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Under normal circumstances, the Adviser seeks to achieve the Fund’s investment objective by investing primarily in established and emerging companies, with capitalizations within the range of companies included in the Russell Midcap® Growth Index, which as of December 31, 2025, ranged between $1.6 billion and $101.9 billion. The Adviser emphasizes a bottom-up stock selection process, seeking attractive investments on an individual company basis. The Adviser typically invests in unique companies it believes have sustainable competitive advantages with above average business visibility, the ability to deploy capital at high rates of return, strong balance sheets and an attractive risk/reward. The Adviser typically focuses a significant portion of the Fund’s investments in a limited number of issuers, which may be in the same industry, sector or geographic region. The Adviser actively integrates sustainability into the investment process by using environmental, social and governance (“ESG”) factors as a lens for additional fundamental research, which can contribute to investment decision-making. The Adviser seeks to understand how environmental and social initiatives within companies can create value by strengthening durable competitive advantages, creating growth opportunities, driving profitability and/or aligning with secular growth trends. The Adviser generally engages with company management teams to discuss their ESG practices, with the aim of identifying how sustainability themes present opportunities and risks that can be material to the value of the security over the long-term. Other aspects of the investment process include a proprietary, systematic evaluation of governance policies, specifically focusing on compensation alignment on long-term value creation. Although consideration of ESG factors is incorporated into the investment process, it is only one of many tools the Adviser utilizes to make investment decisions. The Fund may invest in equity securities. The Fund may also invest in privately placed and restricted securities. The Fund may invest up to 25% of its total assets in securities of foreign issuers, including issuers located in emerging market or developing countries. The securities in which the Fund may invest may be denominated in U.S. dollars or in currencies other than U.S. dollars.
MSIFT Corporate Bond Portfolio - Classes I, A, L, and C \| Corporate Bond Portfolio
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Under normal circumstances, at least 80% of the Fund’s assets will be invested in corporate bonds. This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes. Corporate bonds are fixed-income securities and other debt obligations issued by corporations and other non-governmental issuers. The Fund invests primarily in a diversified mix of U.S. dollar-denominated corporate bonds. The Fund invests primarily in U.S. corporate bonds that carry an investment grade rating (i.e., generally rated Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”), BBB- or higher by S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”), BBB- or higher by Fitch Ratings, Inc. (“Fitch”)) or, if unrated, considered by the Adviser to be of equivalent quality. The Fund may also invest in securities denominated in currencies other than U.S. dollars. The Adviser employs a value approach toward fixed-income investing and evaluates the relative attractiveness of corporate bonds. The Adviser relies upon value measures to guide its decisions regarding sector and security selection, such as the relative attractiveness of the extra yield offered by securities other than those issued by the U.S. Treasury. The Adviser also measures various types of risk by monitoring interest rates, inflation, the shape of the yield curve, credit risk and prepayment risk. The Fund’s investment process incorporates information about environmental, social and governance issues (also referred to as ESG) via an integrated approach within the investment team’s fundamental investment analysis framework. The Adviser may engage with management of certain issuers regarding corporate governance practices as well as what the Adviser deems to be materially important environmental and/or social issues facing a company. When deemed by the Adviser to be relevant to its evaluation of creditworthiness and when applicable information is available, the Adviser considers ESG, which may impact the prospects of an issuer (or obligor) or financial performance of an obligation. When considered, one or more ESG issues are taken into account alongside other factors in the investment decision-making process and are not the sole determinant of whether an investment can be made or will remain in the Fund’s portfolio. The Fund may also invest in restricted and illiquid securities. The Fund may, but it is not required to, use derivative instruments for a variety of purposes, including hedging, risk management, portfolio management or to earn income. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps and other related instruments and techniques. Derivative instruments used by the Fund will be counted towards the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.
MSIFT Ultra-Short Portfolios - Classes IR, Institutional Class, Class A \| Ultra-Short Income Portfolio
Prospectus [Line Items]
Strategy Narrative [Text Block]	The Fund invests primarily in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial issuers and non-financial issuers. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations. Pursuant to a fundamental policy adopted by the Fund, the Fund invests, under normal circumstances, at least 25% of its total assets in securities issued by companies in the financial services industry, including banks, broker-dealers and insurance companies. The Fund may, however, invest less than 25% of its total assets in this industry as a temporary defensive measure. Securities purchased by the Fund (or the issuers of such securities) will carry a rating in the highest two rating categories, A-2, P-2 or F2 or better by S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”), Moody’s Investors Service, Inc. (“Moody’s”), or Fitch Ratings, Inc. (“Fitch”), respectively, or the equivalent by another nationally recognized statistical rating organization (“NRSRO”), or if unrated, considered by the Adviser to be of equivalent quality. The Fund may invest up to 5% of its assets, determined at the time of investment, in securities (or the issuers of such securities) rated A-2, P-2 or F2 by S&P, Moody’s or Fitch, respectively, and no more than 1% of its assets will be invested in an individual security or issuer with such rating. In the case of a security that is rated differently by these three rating agencies, where two rating agencies rate the security in the highest rating category and the third rating agency rates the security in the second highest rating category, the security will be treated as rated in the highest rating category. In the case of a security that is differently rated by only two of these rating agencies, the security will be treated as rated in the lower rating category. Under normal circumstances, the Fund intends to maintain a maximum weighted average maturity of 90 days and a maximum weighted average life of 180 days. The Fund is not a money market fund and does not seek to maintain a stable net asset value per share (“NAV”). The Adviser follows a multi-pronged investment process with respect to credit risk, interest rate risk and liquidity. Securities are reviewed on an ongoing basis to maintain or improve creditworthiness taking into consideration factors such as cash flow, asset quality, debt service coverage ratios and economic developments. Additionally, exposure to guarantors and liquidity providers is monitored separately as are the various diversification requirements. The Adviser manages the Fund’s assets in an attempt to reduce credit and interest rate risks.
MSIFT Global Strategist Portfolio - Classes I, A, L, C and R6 \| Global Strategist Portfolio
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	The Adviser and/or the Fund’s “Sub-Adviser,” Morgan Stanley Investment Management Limited, seek to achieve the Fund’s investment objective by investing primarily in a blend of equity and fixed-income securities of U.S. and non-U.S. issuers. Equity securities may include common and preferred stocks, depositary receipts, convertible securities, equity-linked securities, real estate investment trusts (“REITs”), rights and warrants to purchase equity securities and limited partnership interests. Fixed-income securities may include mortgage-related or mortgage-backed securities, floating rate securities, inflation-linked fixed-income securities, securities issued or guaranteed by the U.S. Government, its agencies or instrumentalities, securities issued or guaranteed by non-U.S. governments, their agencies or instrumentalities, corporate bonds and notes issued by U.S. and non-U.S. entities. The Adviser and/or Sub-Adviser will utilize a top-down investment approach that focuses on asset class, sector, region, country and currency and thematic allocations. The Fund’s allocations will be based upon the Adviser’s and/or Sub-Adviser’s evaluations and analyses, taking into account results of its fundamental market research and recommendations generated by the Adviser’s and/or Sub-Adviser’s quantitative models. The Adviser’s and/or Sub-Adviser’s research process focuses on the following factors across asset classes: 1) valuation (both relative and absolute), 2) dynamics, including earnings revisions, interest rate policy and inflation expectations and 3) technicals, such as investor flows and sentiment. The Fund may invest in any country, including developing or emerging market countries. The Fund’s investments may be U.S. and non-U.S. dollar denominated. In determining whether to sell a security, the Adviser and/or Sub-Adviser consider a number of factors, including changes in capital appreciation potential, or the overall assessment of asset class, sector, region, country, and currency and thematic allocation shifts. The Fund may invest a portion of its assets in below investment grade fixed-income securities (commonly referred to as “junk bonds”). The Fund may also invest in restricted and illiquid securities. The mortgage-backed securities in which the Fund may invest include mortgage pass-through securities that represent a participation interest in a pool of mortgage loans originated by U.S. governmental or private lenders such as banks. The Fund may also invest up to 10% of its total assets in other investment companies, including exchange-traded funds (“ETFs”). The Fund may, but it is not required to, use derivatives and similar instruments for a variety of purposes, including hedging, risk management, Fund management or to earn income. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps and structured investments (including commodity-linked notes), and other similar instruments and techniques. The Fund may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Fund will be counted toward the Fund’s exposure to the types of securities listed above to the extent they have economic characteristics similar to such securities. The Fund may, consistent with its principal investment strategies, invest up to 25% of its total assets in a wholly-owned subsidiary of the Fund organized as a company under the laws of the Cayman Islands (the “Subsidiary”). The Subsidiary may invest, directly or indirectly through the use of derivatives, in securities, commodities, commodity-related instruments and other investments, primarily futures, swaps and notes. The Subsidiary is advised by the Adviser. Investments in the Subsidiary are intended to provide the Fund with exposure to commodities markets within the limitations of the federal tax requirements that apply to the Fund. The Subsidiary primarily obtains its commodity exposure by investing in commodity-linked derivative instruments, which may include, but are not limited to, total return swaps, commodity (U.S. or foreign) futures and commodity-linked notes. The Subsidiary may also invest in other instruments, including fixed-income securities, either as investments or to serve as margin or collateral for its swap positions and foreign currency transactions (including forward contracts).

Investment Strategy

Sep. 30, 2025

Principal Investment Strategies

Under normal circumstances, the Adviser seeks to achieve the Fund’s investment objective by investing primarily in established and emerging companies, with capitalizations within the range of companies included in the Russell Midcap® Growth Index, which as of December 31, 2025, ranged between $1.6 billion and $101.9 billion.

The Adviser emphasizes a bottom-up stock selection process, seeking attractive investments on an individual company basis. The Adviser typically invests in unique companies it believes have sustainable competitive advantages with above average business visibility, the ability to deploy capital at high rates of return, strong balance sheets and an attractive risk/reward. The Adviser typically focuses a significant portion of the Fund’s investments in a limited number of issuers, which may be in the same industry, sector or geographic region.

The Adviser actively integrates sustainability into the investment process by using environmental, social and governance (“ESG”) factors as a lens for additional fundamental research, which can contribute to investment decision-making. The Adviser seeks to understand how environmental and social initiatives within companies can create value by strengthening durable competitive advantages, creating growth opportunities, driving profitability and/or aligning with secular growth trends. The Adviser generally engages with company management teams to discuss their ESG practices, with the aim of identifying how sustainability themes present opportunities and risks that can be material to the value of the security over the long-term. Other aspects of the investment process include a proprietary, systematic evaluation of governance policies, specifically focusing on compensation alignment on long-term value creation. Although consideration of ESG factors is incorporated into the investment process, it is only one of many tools the Adviser utilizes to make investment decisions.

The Fund may invest in equity securities. The Fund may also invest in privately placed and restricted securities.

The Fund may invest up to 25% of its total assets in securities of foreign issuers, including issuers located in emerging market or developing countries. The securities in which the Fund may invest may be denominated in U.S. dollars or in currencies other than U.S. dollars.

MSIFT Corporate Bond Portfolio - Classes I, A, L, and C | Corporate Bond Portfolio

Prospectus [Line Items]

Strategy [Heading]

Principal Investment Strategies

Strategy Narrative [Text Block]

Under normal circumstances, at least 80% of the Fund’s assets will be invested in corporate bonds. This policy may be changed without shareholder approval; however, you would be notified upon 60 days’ notice in writing of any changes. Corporate bonds are fixed-income securities and other debt obligations issued by corporations and other non-governmental issuers. The Fund invests primarily in a diversified mix of U.S. dollar-denominated corporate bonds. The Fund invests primarily in U.S. corporate bonds that carry an investment grade rating (i.e., generally rated Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”), BBB- or higher by S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”), BBB- or higher by Fitch Ratings, Inc. (“Fitch”)) or, if unrated, considered by the Adviser to be of equivalent quality. The Fund may also invest in securities denominated in currencies other than U.S. dollars.

The Adviser employs a value approach toward fixed-income investing and evaluates the relative attractiveness of corporate bonds. The Adviser relies upon value measures to guide its decisions regarding sector and security selection, such as the relative attractiveness of the extra yield offered by securities other than those issued by the U.S. Treasury. The Adviser also measures various types of risk by monitoring interest rates, inflation, the shape of the yield curve, credit risk and prepayment risk.

The Fund’s investment process incorporates information about environmental, social and governance issues (also referred to as ESG) via an integrated approach within the investment team’s fundamental investment analysis framework. The Adviser may engage with management of certain issuers regarding corporate governance practices as well as what the Adviser deems to be materially important environmental and/or social issues facing a company. When deemed by the Adviser to be relevant to its evaluation of creditworthiness and when applicable information is available, the Adviser considers ESG, which may impact the prospects of an issuer (or obligor) or financial performance of an obligation. When considered, one or more ESG issues are taken into account alongside other factors in the investment decision-making process and are not the sole determinant of whether an investment can be made or will remain in the Fund’s portfolio.

The Fund may also invest in restricted and illiquid securities.

The Fund may, but it is not required to, use derivative instruments for a variety of purposes, including hedging, risk management, portfolio management or to earn income. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps and other related instruments and techniques. Derivative instruments used by the Fund will be counted towards the Fund’s 80% policy discussed above to the extent they have economic characteristics similar to the securities included within that policy.

MSIFT Ultra-Short Portfolios - Classes IR, Institutional Class, Class A | Ultra-Short Income Portfolio

Prospectus [Line Items]

Strategy Narrative [Text Block]

The Fund invests primarily in liquid, high quality U.S. dollar-denominated money market instruments of U.S. and foreign financial issuers and non-financial issuers. The Fund also invests in obligations issued or guaranteed by the U.S. Government and its agencies and instrumentalities. The Fund’s money market investments may include commercial paper, corporate debt obligations, debt obligations (including certificates of deposit and promissory notes) of U.S. banks or foreign banks, or of U.S. branches or subsidiaries of foreign banks, or foreign branches of U.S. banks (such as Yankee obligations), certificates of deposit of savings banks and savings and loan organizations, asset-backed securities, repurchase agreements and municipal obligations.

Pursuant to a fundamental policy adopted by the Fund, the Fund invests, under normal circumstances, at least 25% of its total assets in securities issued by companies in the financial services industry, including banks, broker-dealers and insurance companies. The Fund may, however, invest less than 25% of its total assets in this industry as a temporary defensive measure.

Securities purchased by the Fund (or the issuers of such securities) will carry a rating in the highest two rating categories, A-2, P-2 or F2 or better by S&P Global Ratings Group, a division of S&P Global Inc. (“S&P”), Moody’s Investors Service, Inc. (“Moody’s”), or Fitch Ratings, Inc. (“Fitch”), respectively, or the equivalent by another nationally recognized statistical rating organization (“NRSRO”), or if unrated, considered by the Adviser to be of equivalent quality. The Fund may invest up to 5% of its assets, determined at the time of investment, in securities (or the issuers of such securities) rated A-2, P-2 or F2 by S&P, Moody’s or Fitch, respectively, and no more than 1% of its assets will be invested in an individual security or issuer with such rating. In the case of a security that is rated differently by these three rating agencies, where two rating agencies rate the security in the highest rating category and the third rating agency rates the security in the second highest rating category, the security will be treated as rated in the highest rating category. In the case of a security that is differently rated by only two of these rating agencies, the security will be treated as rated in the lower rating category.

Under normal circumstances, the Fund intends to maintain a maximum weighted average maturity of 90 days and a maximum weighted average life of 180 days.

The Fund is not a money market fund and does not seek to maintain a stable net asset value per share (“NAV”).

The Adviser follows a multi-pronged investment process with respect to credit risk, interest rate risk and liquidity. Securities are reviewed on an ongoing basis to maintain or improve creditworthiness taking into consideration factors such as cash flow, asset quality, debt service coverage ratios and economic developments. Additionally, exposure to guarantors and liquidity providers is monitored separately as are the various diversification requirements. The Adviser manages the Fund’s assets in an attempt to reduce credit and interest rate risks.

MSIFT Global Strategist Portfolio - Classes I, A, L, C and R6 | Global Strategist Portfolio

Prospectus [Line Items]

Strategy [Heading]

Principal Investment Strategies

Strategy Narrative [Text Block]

The Adviser and/or the Fund’s “Sub-Adviser,” Morgan Stanley Investment Management Limited, seek to achieve the Fund’s investment objective by investing primarily in a blend of equity and fixed-income securities of U.S. and non-U.S. issuers. Equity securities may include common and preferred stocks, depositary receipts, convertible securities, equity-linked securities, real estate investment trusts (“REITs”), rights and warrants to purchase equity securities and limited partnership interests. Fixed-income securities may include mortgage-related or mortgage-backed securities, floating rate securities, inflation-linked fixed-income securities, securities issued or guaranteed by the U.S. Government, its agencies or instrumentalities, securities issued or guaranteed by non-U.S. governments, their agencies or instrumentalities, corporate bonds and notes issued by U.S. and non-U.S. entities.

The Adviser and/or Sub-Adviser will utilize a top-down investment approach that focuses on asset class, sector, region, country and currency and thematic allocations. The Fund’s allocations will be based upon the Adviser’s and/or Sub-Adviser’s evaluations and analyses, taking into account results of its fundamental market research and recommendations generated by the Adviser’s and/or Sub-Adviser’s quantitative models. The Adviser’s and/or Sub-Adviser’s research process focuses on the following factors across asset classes: 1) valuation (both relative and absolute), 2) dynamics, including earnings revisions, interest rate policy and inflation expectations and 3) technicals, such as investor flows and sentiment. The Fund may invest in any country, including developing or emerging market countries. The Fund’s investments may be U.S. and non-U.S. dollar denominated. In determining whether to sell a security, the Adviser and/or Sub-Adviser consider a number of factors, including changes in capital appreciation potential, or the overall assessment of asset class, sector, region, country, and currency and thematic allocation shifts.

The Fund may invest a portion of its assets in below investment grade fixed-income securities (commonly referred to as “junk bonds”). The Fund may also invest in restricted and illiquid securities. The mortgage-backed securities in which the Fund may invest include mortgage pass-through securities that represent a participation interest in a pool of mortgage loans originated by U.S. governmental or private lenders such as banks.

The Fund may also invest up to 10% of its total assets in other investment companies, including exchange-traded funds (“ETFs”).

The Fund may, but it is not required to, use derivatives and similar instruments for a variety of purposes, including hedging, risk management, Fund management or to earn income. The Fund’s use of derivatives may involve the purchase and sale of derivative instruments such as futures, options, swaps and structured investments (including commodity-linked notes), and other similar instruments and techniques. The Fund may utilize foreign currency forward exchange contracts, which are also derivatives, in connection with its investments in foreign securities. Derivative instruments used by the Fund will be counted toward the Fund’s exposure to the types of securities listed above to the extent they have economic characteristics similar to such securities.

The Fund may, consistent with its principal investment strategies, invest up to 25% of its total assets in a wholly-owned subsidiary of the Fund organized as a company under the laws of the Cayman Islands (the “Subsidiary”). The Subsidiary may invest, directly or indirectly through the use of derivatives, in securities, commodities, commodity-related instruments and other investments, primarily futures, swaps and notes. The Subsidiary is advised by the Adviser.

Investments in the Subsidiary are intended to provide the Fund with exposure to commodities markets within the limitations of the federal tax requirements that apply to the Fund. The Subsidiary primarily obtains its commodity exposure by investing in commodity-linked derivative instruments, which may include, but are not limited to, total return swaps, commodity (U.S. or foreign) futures and commodity-linked notes. The Subsidiary may also invest in other instruments, including fixed-income securities, either as investments or to serve as margin or collateral for its swap positions and foreign currency transactions (including forward contracts).