| Label | Element | Value | ||||||
|---|---|---|---|---|---|---|---|---|
| MFS Global Opportunistic Bond Fund | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk/Return [Heading] | rr_RiskReturnHeading | MFS® Global Opportunistic Bond Fund Summary of Key Information | ||||||
| Objective [Heading] | rr_ObjectiveHeading | Investment Objective | ||||||
| Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | The fund’s investment objective is to seek total return with an emphasis on current income, but also considering capital appreciation. |
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| Expense [Heading] | rr_ExpenseHeading | Fees and Expenses | ||||||
| Expense Narrative [Text Block] | rr_ExpenseNarrativeTextBlock | This table describes the fees and expenses that you may pay when you buy, hold, and sell shares of the fund. Investors may also pay commissions or other fees to their financial intermediaries when they buy, hold, and sell shares of the fund, which are not reflected below. You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. More information about these and other waivers and reductions is available from your financial intermediary and in “Sales Charges and Waivers and Reductions” on page 12 and “Appendix A – Waivers and Reductions of Sales Charges” on page A-1 of the fund’s prospectus. |
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| Shareholder Fees Caption [Text] | rr_ShareholderFeesCaption | Shareholder Fees (fees paid directly from your investment): | ||||||
| Operating Expenses Caption [Text] | rr_OperatingExpensesCaption | Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment): | ||||||
| Portfolio Turnover [Heading] | rr_PortfolioTurnoverHeading | Portfolio Turnover | ||||||
| Portfolio Turnover [Text Block] | rr_PortfolioTurnoverTextBlock | The fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These transaction costs, which are not reflected in “Annual Fund Operating Expenses” or in the “Example,” affect the fund’s performance. During the most recent fiscal year, the fund’s portfolio turnover rate was 146% of the average value of its portfolio (114% excluding to be announced (TBA) transactions). |
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| Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 146.00% | ||||||
| Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge reductions if, with respect to Class A shares, you and certain members of your family invest, or agree to invest in the future, at least $100,000 in MFS funds. | ||||||
| Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | $ 100,000 | ||||||
| Expense Example [Heading] | rr_ExpenseExampleHeading | Example | ||||||
| Expense Example Narrative [Text Block] | rr_ExpenseExampleNarrativeTextBlock | This example is intended to help you compare the cost of investing in the fund with the cost of investing in other mutual funds. The example assumes that: you invest $10,000 in the fund for the time periods indicated and you redeem your shares at the end of the time periods (unless otherwise indicated); your investment has a 5% return each year; and the fund’s operating expenses remain the same. |
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| Expense Example by, Year, Caption [Text] | rr_ExpenseExampleByYearCaption | Although your actual costs will likely be higher or lower, under these assumptions your costs would be: | ||||||
| Strategy [Heading] | rr_StrategyHeading | Principal Investment Strategies | ||||||
| Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | MFS (Massachusetts Financial Services Company, the fund's investment adviser) normally invests at least 80% of the fund’s net assets in debt instruments of U.S. and foreign issuers, including emerging markets issuers. Debt instruments include U.S. Government securities, corporate bonds, foreign government securities, securitized instruments (including mortgage-backed securities and other asset-backed securities), and other obligations to repay money borrowed. While MFS may invest the fund’s assets in debt instruments of any type, MFS generally focuses on debt instruments of issuers located in developed markets. MFS generally focuses on investment grade quality debt instruments, but may also invest the fund’s assets in below investment grade quality debt instruments. MFS normally enters into currency hedging transactions using derivatives to reduce the fund’s foreign currency exposure such that the fund is primarily exposed to the U.S. dollar. MFS normally invests the fund's assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of the fund’s assets in issuers in a single industry, sector, country, or region. MFS generally invests the fund's assets in at least three different countries and invests a percentage of the fund's net assets in securities of foreign issuers equal to at least the lesser of 40% or the percentage of foreign issuers in the Bloomberg Global Aggregate Index (USD Hedged) less 15%. MFS may invest up to 35% of the fund’s assets in any industry that accounts for more than 20% of the global bond market as measured by an index determined by MFS to be an appropriate measure of the global bond market, currently the Bloomberg Global Aggregate Index (USD Hedged). While MFS may use derivatives for any investment purpose, to the extent MFS uses derivatives, MFS expects to use derivatives primarily to increase or decrease exposure to a particular market, segment of the market, or security, to increase or decrease interest rate or currency exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, and swaps. MFS uses an active bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual instruments and their issuers. Quantitative screening tools that systematically evaluate instruments may also be considered. In structuring the fund, MFS also considers top-down factors. For purposes of the fund's 80% policy, net assets include the amount of any borrowings for investment purposes. |
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| Risk [Heading] | rr_RiskHeading | Principal Risks | ||||||
| Bar Chart and Performance Table [Heading] | rr_BarChartAndPerformanceTableHeading | Performance Information | ||||||
| Performance Narrative [Text Block] | rr_PerformanceNarrativeTextBlock | The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund’s performance over time compares with that of a broad measure of market performance. Performance information prior to April 30, 2021, reflects time periods when the fund (i) had a policy of primarily investing in investment grade quality debt instruments and (ii) did not have a policy to engage in a currency hedging strategy to primarily expose the fund to the U.S. dollar. The fund’s investment policies and strategies changed effective April 30, 2021. The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. Updated performance is available online at mfs.com or by calling 1-800-225-2606. |
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| Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | The bar chart and performance table below are intended to provide some indication of the risks of investing in the fund by showing changes in the fund’s performance over time and how the fund’s performance over time compares with that of a broad measure of market performance. | ||||||
| Performance Availability Phone [Text] | rr_PerformanceAvailabilityPhone | 1-800-225-2606 | ||||||
| Performance Availability Website Address [Text] | rr_PerformanceAvailabilityWebSiteAddress | mfs.com | ||||||
| Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | The fund’s past performance (before and after taxes) does not necessarily indicate how the fund will perform in the future. | ||||||
| Bar Chart [Heading] | rr_BarChartHeading | Class A Bar Chart. | ||||||
| Bar Chart Narrative [Text Block] | rr_BarChartNarrativeTextBlock | The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. | ||||||
| Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | The bar chart does not take into account any sales charges (loads) that you may be required to pay upon purchase or redemption of the fund’s shares. If these sales charges were included, they would reduce the returns shown. | ||||||
| Bar Chart Closing [Text Block] | rr_BarChartClosingTextBlock | During the period(s) shown in the bar chart, the highest quarterly return was 8.03% (for the calendar quarter ended December 31, 2023) and the lowest quarterly return was (7.30)% (for the calendar quarter ended December 31, 2016). |
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| Performance Table Heading | rr_PerformanceTableHeading | Performance Table. | ||||||
| Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. | ||||||
| Performance Table Not Relevant to Tax Deferred | rr_PerformanceTableNotRelevantToTaxDeferred | Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). | ||||||
| Performance Table One Class of after Tax Shown [Text] | rr_PerformanceTableOneClassOfAfterTaxShown | The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. | ||||||
| Performance Table Closing [Text Block] | rr_PerformanceTableClosingTextBlock | After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your own tax situation, and may differ from those shown. The after-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (IRAs). The after-tax returns are shown for only one of the fund’s classes of shares, and after-tax returns for the fund’s other classes of shares will vary from the returns shown. |
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| Average Annual Return, Caption | rr_AverageAnnualReturnCaption | Average Annual Total Returns (For the Periods Ended December 31, 2024) | ||||||
| MFS Global Opportunistic Bond Fund | Principal Risks | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Principal Risks As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. The principal risks of investing in the fund are: |
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| MFS Global Opportunistic Bond Fund | Risk Lose Money [Member] | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund. | ||||||
| MFS Global Opportunistic Bond Fund | Risk Not Insured [Member] | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | An investment in the fund is not a bank deposit and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency. | ||||||
| MFS Global Opportunistic Bond Fund | Investment Selection Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Investment Selection Risk: MFS' investment analysis and its selection of investments may not produce the intended results and/or can lead to an investment focus that results in the fund underperforming other funds with similar investment strategies and/or underperforming the markets in which the fund invests. In addition, to the extent MFS considers quantitative tools in managing the fund, such tools may not produce the intended results. |
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| MFS Global Opportunistic Bond Fund | Debt Market Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Debt Market Risk: Debt markets can be volatile and can decline significantly in response to changes in, or investor perceptions of, issuer, market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These conditions can affect a single instrument, issuer, or borrower, a particular type of instrument, issuer, or borrower, a segment of the debt markets or the debt markets generally. Certain events can have a dramatic adverse effect on debt markets and may lead to periods of high volatility and reduced liquidity in a debt market or segment of a debt market. |
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| MFS Global Opportunistic Bond Fund | Interest Rate Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Interest Rate Risk: In general, the price of a debt instrument falls when interest rates rise and rises when interest rates fall. Interest rate risk is generally greater for instruments with longer maturities or durations, or that do not pay current interest. |
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| MFS Global Opportunistic Bond Fund | Credit Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Credit Risk: The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or other entity responsible for payment, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in, or perceptions of, the financial condition of the issuer, borrower, counterparty, or other entity, or underlying collateral or assets, or changes in, or perceptions of, specific or general market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. Debt instruments may be more susceptible to downgrades or defaults during economic downturns or similar periods of economic stress, which in turn could negatively affect the market value and liquidity of a debt instrument. Below investment grade quality debt instruments (commonly referred to as “high yield securities” or “junk bonds”) can involve a substantially greater risk of default or can already be in default, and their values can decline significantly. Below investment grade quality debt instruments are regarded as having predominantly speculative characteristics. Below investment grade quality debt instruments tend to be more sensitive to adverse news about the issuer, or the market or economy in general, than higher quality debt instruments. |
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| MFS Global Opportunistic Bond Fund | Foreign Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Foreign Risk: Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions. These factors can make foreign investments, especially those tied economically to emerging markets or countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market. |
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| MFS Global Opportunistic Bond Fund | Emerging Markets Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Emerging Markets Risk: Investments tied economically to emerging markets, especially frontier markets, can involve additional and greater risks than the risks associated with investments in developed markets. Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, greater government involvement in the economy, greater risk of new or inconsistent government treatment of or restrictions on issuers and instruments, and greater political, social, geopolitical, and economic instability than developed markets. |
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| MFS Global Opportunistic Bond Fund | Currency Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Currency Risk: The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, environmental, public health, and other conditions, and changes in currency exchange rates impact the financial condition of companies or other issuers and may change the value in U.S. dollars of investments denominated in foreign currencies. The use of foreign exchange contracts to reduce foreign currency exposure will not completely eliminate the exposure to foreign currency movements. In addition, the use of foreign exchange contracts to reduce foreign currency exposure can eliminate some or all of the benefit of an increase in the value of a foreign currency versus the U.S. dollar. |
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| MFS Global Opportunistic Bond Fund | Prepayment/Extension Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Prepayment/Extension Risk: Instruments subject to prepayment and/or extension can reduce the potential for gain for the instrument’s holders if the instrument is prepaid and increase the potential for loss if the maturity of the instrument is extended. |
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| MFS Global Opportunistic Bond Fund | Focus Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Focus Risk: Issuers in a single industry, sector, country, or region can react similarly to market, currency, political, economic, regulatory, geopolitical, environmental, public health, and other conditions, and the fund's performance will be affected by the conditions in the industries, sectors, countries, and regions to which the fund is exposed. |
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| MFS Global Opportunistic Bond Fund | Industry Concentration Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Industry Concentration Risk: The fund’s performance may be closely tied to the performance of issuers in any industry that accounts for a significant portion of the global bond market. |
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| MFS Global Opportunistic Bond Fund | Derivatives Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Derivatives Risk: Derivatives can be highly volatile and involve risks in addition to the risks of the underlying indicator(s) on which the derivative is based. Gains or losses from derivatives can be substantially greater than the derivatives’ original cost. Derivatives can involve leverage. |
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| MFS Global Opportunistic Bond Fund | Leveraging Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses. |
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| MFS Global Opportunistic Bond Fund | Counterparty and Third Party Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Counterparty and Third Party Risk: Transactions involving a counterparty or third party other than the issuer of the instrument are subject to the credit risk of the counterparty or third party, and to the counterparty’s or third party’s ability or willingness to perform in accordance with the terms of the transaction. |
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| MFS Global Opportunistic Bond Fund | Liquidity Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Liquidity Risk: It may be difficult to value, and it may not be possible to sell, certain investments, types of investments, and/or investments in certain segments of the market, and the fund may have to sell certain of these investments at prices or times that are not advantageous in order to meet redemptions or other cash needs. |
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| MFS Global Opportunistic Bond Fund | Large Shareholder Risk | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Risk [Text Block] | rr_RiskTextBlock | Large Shareholder Risk: From time to time, shareholders of the fund (which may include institutional investors, financial intermediaries, or other MFS funds) may make relatively large redemptions or purchases of fund shares. These transactions may cause the fund to sell securities or invest additional cash, as the case may be, at disadvantageous prices. Redemptions of a large number of shares also may increase transaction and other costs or have adverse tax consequences for shareholders of the fund by requiring a sale of portfolio securities. Purchases of a large number of shares may adversely affect the fund's performance to the extent that it takes time to invest new cash and the fund maintains a larger cash position than it ordinarily would. |
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| MFS Global Opportunistic Bond Fund | Bloomberg Global Aggregate Index (USD Hedged) | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Index No Deduction for Fees, Expenses, Taxes [Text] | rr_IndexNoDeductionForFeesExpensesTaxes | Reflects no deduction for fees, expenses, or taxes | ||||||
| Label | rr_AverageAnnualReturnLabel | Bloomberg Global Aggregate Index (USD Hedged) | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 3.40% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.48% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 2.01% | ||||||
| MFS Global Opportunistic Bond Fund | Class A | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBAX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 4.25% | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | [1] | |||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.95% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.94% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| Expenses Deferred Charges [Text Block] | rr_ExpensesDeferredChargesTextBlock | This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase. | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 517 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 714 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 927 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 1,541 | ||||||
| Annual Return 2015 | rr_AnnualReturn2015 | (4.57%) | ||||||
| Annual Return 2016 | rr_AnnualReturn2016 | 2.33% | ||||||
| Annual Return 2017 | rr_AnnualReturn2017 | 7.58% | ||||||
| Annual Return 2018 | rr_AnnualReturn2018 | (2.39%) | ||||||
| Annual Return 2019 | rr_AnnualReturn2019 | 8.13% | ||||||
| Annual Return 2020 | rr_AnnualReturn2020 | 10.71% | ||||||
| Annual Return 2021 | rr_AnnualReturn2021 | (3.21%) | ||||||
| Annual Return 2022 | rr_AnnualReturn2022 | (11.12%) | ||||||
| Annual Return 2023 | rr_AnnualReturn2023 | 8.35% | ||||||
| Annual Return 2024 | rr_AnnualReturn2024 | 2.43% | ||||||
| Label | rr_HighestQuarterlyReturnLabel | highest quarterly return | ||||||
| Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Dec. 31, 2023 | ||||||
| Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 8.03% | ||||||
| Label | rr_LowestQuarterlyReturnLabel | lowest quarterly return | ||||||
| Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Dec. 31, 2016 | ||||||
| Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (7.30%) | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | (1.92%) | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.24% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.16% | ||||||
| MFS Global Opportunistic Bond Fund | Class A | After Taxes on Distributions | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Label | rr_AverageAnnualReturnLabel | Returns After Taxes on Distributions | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | (3.12%) | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | (0.91%) | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 0.34% | ||||||
| MFS Global Opportunistic Bond Fund | Class A | After Taxes on Distributions and Sales | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Label | rr_AverageAnnualReturnLabel | Returns After Taxes on Distributions and Sale of Fund Shares | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | (1.15%) | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | (0.20%) | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 0.58% | ||||||
| MFS Global Opportunistic Bond Fund | Class B | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBBX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 4.00% | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.70% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.69% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 572 | [3] | |||||
| 3 Years | rr_ExpenseExampleYear03 | 835 | [3] | |||||
| 5 Years | rr_ExpenseExampleYear05 | 1,122 | [3] | |||||
| 10 Years | rr_ExpenseExampleYear10 | 1,809 | [3] | |||||
| 1 Year | rr_ExpenseExampleNoRedemptionYear01 | 172 | [3] | |||||
| 3 Years | rr_ExpenseExampleNoRedemptionYear03 | 535 | [3] | |||||
| 5 Years | rr_ExpenseExampleNoRedemptionYear05 | 922 | [3] | |||||
| 10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 1,809 | [3] | |||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | (2.31%) | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | none | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.00% | ||||||
| MFS Global Opportunistic Bond Fund | Class C | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBDX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.70% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.69% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 272 | [3] | |||||
| 3 Years | rr_ExpenseExampleYear03 | 535 | [3] | |||||
| 5 Years | rr_ExpenseExampleYear05 | 922 | [3] | |||||
| 10 Years | rr_ExpenseExampleYear10 | 1,809 | [3] | |||||
| 1 Year | rr_ExpenseExampleNoRedemptionYear01 | 172 | [3] | |||||
| 3 Years | rr_ExpenseExampleNoRedemptionYear03 | 535 | [3] | |||||
| 5 Years | rr_ExpenseExampleNoRedemptionYear05 | 922 | [3] | |||||
| 10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 1,809 | [3] | |||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 0.55% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.33% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.00% | ||||||
| MFS Global Opportunistic Bond Fund | Class I | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBJX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.70% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.69% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 70 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 223 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 389 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 870 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 2.69% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.34% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.86% | ||||||
| MFS Global Opportunistic Bond Fund | Class R1 | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBKX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.70% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.69% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 172 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 535 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 922 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 2,008 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 1.54% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.33% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 0.85% | ||||||
| MFS Global Opportunistic Bond Fund | Class R2 | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBLX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.50% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.20% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.19% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 121 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 380 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 659 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 1,454 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 2.05% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 0.86% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.35% | ||||||
| MFS Global Opportunistic Bond Fund | Class R3 | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBMX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.95% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.94% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 96 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 302 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 525 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 1,165 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 2.30% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.09% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.60% | ||||||
| MFS Global Opportunistic Bond Fund | Class R4 | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBNX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.70% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.69% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 70 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 223 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 389 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 870 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 2.56% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.36% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.86% | ||||||
| MFS Global Opportunistic Bond Fund | Class R6 | ||||||||
| Risk/Return: | rr_RiskReturnAbstract | |||||||
| Trading Symbol | dei_TradingSymbol | MGBOX | ||||||
| Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||
| Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||
| Management Fee | rr_ManagementFeesOverAssets | 0.55% | ||||||
| Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||
| Other Expenses | rr_OtherExpensesOverAssets | 0.07% | ||||||
| Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.62% | ||||||
| Fee Reductions and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.01%) | [2] | |||||
| Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.61% | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | March 31, 2026 | ||||||
| 1 Year | rr_ExpenseExampleYear01 | $ 62 | ||||||
| 3 Years | rr_ExpenseExampleYear03 | 198 | ||||||
| 5 Years | rr_ExpenseExampleYear05 | 345 | ||||||
| 10 Years | rr_ExpenseExampleYear10 | $ 773 | ||||||
| Label | rr_AverageAnnualReturnLabel | Returns Before Taxes | ||||||
| 1 Year | rr_AverageAnnualReturnYear01 | 2.64% | ||||||
| 5 Years | rr_AverageAnnualReturnYear05 | 1.45% | ||||||
| 10 Years | rr_AverageAnnualReturnYear10 | 1.97% | ||||||
| ||||||||