v3.26.3
Label Element Value
MFS International Diversification Fund  
Risk/Return: oef_RiskReturnAbstract  
Risk/Return [Heading] oef_RiskReturnHeading MFS® International Diversification Fund Summary of Key Information
Objective [Heading] oef_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] oef_ObjectivePrimaryTextBlock

The fund’s investment objective is to seek capital appreciation.

Expense Heading [Optional Text] oef_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] oef_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 $50,000 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 11 and “Appendix A – Waivers and Reductions of Sales Charges” on page A-1 of the fund’s prospectus.

Shareholder Fees Caption [Optional Text] oef_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment):
Operating Expenses Caption [Optional Text] oef_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment):
Portfolio Turnover [Heading] oef_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] oef_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 1% of the average value of its portfolio.
Portfolio Turnover, Rate oef_PortfolioTurnoverRate 1.00%
Expense Breakpoint Discounts [Text] oef_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 $50,000 in MFS funds.
Expense Breakpoint, Minimum Investment Required [Amount] oef_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expense Example [Heading] oef_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] oef_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.

Expense Example by, Year, Caption [Text] oef_ExpenseExampleByYearCaption Although your actual costs will likely be higher or lower, under these assumptions your costs would be:
Strategy [Heading] oef_StrategyHeading Principal Investment Strategies
Strategy Narrative [Text Block] oef_StrategyNarrativeTextBlock

The fund is designed to provide diversification within the international asset class by investing the majority of its assets in other mutual funds advised by MFS (Massachusetts Financial Services Company, the fund’s investment adviser), referred to as underlying funds. The underlying funds are selected based on underlying fund classifications, historical risk, performance, and other factors. MFS seeks to diversify the fund's investments in terms of market capitalization (by including large, mid, and/or small cap underlying funds), by style (by including both growth and value underlying funds), and by geography (by including developed and emerging market underlying funds). MFS normally invests each underlying fund's assets across different industries, sectors, countries, and regions, but MFS may invest a significant percentage of an underlying fund's assets in issuers in a single industry, sector, country, or region.

As of September 1, 2026, the fund’s target allocation among underlying funds was:

  

MFS Emerging Markets Equity Fund

17.5%

MFS International Growth Fund

15%

MFS International Intrinsic Equity Fund1

15%

MFS International New Discovery Fund

10%

MFS International Value Fund2

15%

MFS Research International Fund

27.5%

1 Effective April 30, 2026, the name of MFS International Intrinsic Value Fund changed to MFS International Intrinsic Equity Fund.

2 Effective August 1, 2026, the name of MFS International Large Cap Value Fund changed to MFS International Value Fund.
Bar Chart and Performance Table [Heading] oef_BarChartAndPerformanceTableHeading Performance Information
Performance Narrative [Text Block] oef_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.

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.
Performance Information Illustrates Variability of Returns [Text] oef_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] oef_PerformanceAvailabilityPhone 1-800-225-2606
Performance Availability Website Address [Text] oef_PerformanceAvailabilityWebSiteAddress mfs.com
Performance Past Does Not Indicate Future [Text] oef_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] oef_BarChartHeading Class A Bar Chart.
Bar Chart Narrative [Text Block] oef_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] oef_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] oef_BarChartClosingTextBlock

The total return for the six-month period ended June 30, 2026, was 8.76%. During the period(s) shown in the bar chart, the highest quarterly return was 17.04% (for the calendar quarter ended June 30, 2020) and the lowest quarterly return was (19.80)% (for the calendar quarter ended March 31, 2020).
Performance Table Heading oef_PerformanceTableHeading Performance Table.
Index No Deduction for Fees, Expenses, or Taxes [Text] oef_IndexNoDeductionForFeesExpensesTaxes Reflects no deduction for fees, expenses, or taxes
Performance Table Not Relevant to Tax Deferred oef_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] oef_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] oef_PerformanceTableClosingTextBlock

After-tax returns are calculated using the historical highest individual U.S. 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.
Average Annual Return, Caption [Optional Text] oef_AverageAnnualReturnCaption Average Annual Total Returns (For the Periods Ended December 31, 2025)
MFS International Diversification Fund | Principal Risks  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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:
MFS International Diversification Fund | Risk Lose Money [Member]  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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 International Diversification Fund | Risk Not Insured [Member]  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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 International Diversification Fund | Allocation Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Allocation Risk: MFS' assessment of the risk/return potential of asset classes and underlying funds, and the resulting allocation among asset classes and underlying funds, 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.
MFS International Diversification Fund | Underlying Funds Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Underlying Funds Risk: MFS' strategy of investing in underlying funds exposes the fund to the risks of the underlying funds. Each underlying fund pursues its own investment objective and strategies and may not achieve its objective. In addition to the fees and expenses the fund bears directly, shareholders of the fund will indirectly bear the fees and expenses of the underlying funds.
MFS International Diversification Fund | Investment Selection Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Investment Selection Risk: MFS' investment analysis, including its assessment of the intrinsic valuation of issuers, 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.

MFS International Diversification Fund | Equity Market Risk/Company Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Equity Market Risk/Company Risk: Equity markets are 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 issuer or type of security, issuers within a broad market sector, industry or geographic region, or the equity markets in general. Certain events can have a dramatic adverse effect on equity markets and may lead to periods of high volatility in an equity market or a segment of an equity market. The value of an investment held by the fund may decline due to factors directly related to the issuer.
MFS International Diversification Fund | Growth Company Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Growth Company Risk: The stocks of growth companies can be more sensitive to the company’s earnings and more volatile than the market in general.
MFS International Diversification Fund | Value Company Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Value Company Risk: The stocks of value companies can continue to be undervalued for long periods of time and not realize their expected value and can be more volatile than the market in general.

 
MFS International Diversification Fund | Focus Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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. Furthermore, investments in particular industries, sectors, countries, or regions may be more volatile than the broader market as a whole.

MFS International Diversification Fund | Foreign Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.

MFS International Diversification Fund | Emerging Markets Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.

MFS International Diversification Fund | Currency Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.

MFS International Diversification Fund | Derivatives Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.
MFS International Diversification Fund | Leveraging Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_RiskTextBlock

Leveraging Risk: Leverage involves investment exposure in an amount exceeding the initial investment. Leverage can cause increased volatility by magnifying gains or losses.

MFS International Diversification Fund | Counterparty and Third Party Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.
MFS International Diversification Fund | Liquidity Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.

MFS International Diversification Fund | Large Shareholder Risk  
Risk/Return: oef_RiskReturnAbstract  
Risk [Text Block] oef_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.
MFS International Diversification Fund | MSCI All Country World (ex-US) Index (net div)  
Risk/Return: oef_RiskReturnAbstract  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel MSCI All Country World (ex-US) Index (net div)
Average Annual Return, Percent oef_AvgAnnlRtrPct 32.39%
Average Annual Return, Percent oef_AvgAnnlRtrPct 7.91%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.41%
MFS International Diversification Fund | Class A  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIDX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 1.00% [1]
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.08%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.07%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expenses Deferred Charges [Text Block] oef_ExpensesDeferredChargesTextBlock This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 678
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 898
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 1,135
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 1,816
Year to Date Return, Label [Optional Text] oef_YearToDateReturnLabel The total return for the six-month period ended
Bar Chart, Year to Date Return, Date oef_BarChartYearToDateReturnDate Jun. 30, 2026
Bar Chart, Year to Date Return oef_BarChartYearToDateReturn 8.76%
Highest Quarterly Return, Label [Optional Text] oef_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date oef_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return oef_BarChartHighestQuarterlyReturn 17.04%
Lowest Quarterly Return, Label [Optional Text] oef_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date oef_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return oef_BarChartLowestQuarterlyReturn (19.80%)
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 20.21%
Average Annual Return, Percent oef_AvgAnnlRtrPct 5.26%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.20%
Annual Return [Percent] oef_AnnlRtrPct 2.16%
Annual Return [Percent] oef_AnnlRtrPct 29.94%
Annual Return [Percent] oef_AnnlRtrPct (11.24%)
Annual Return [Percent] oef_AnnlRtrPct 25.68%
Annual Return [Percent] oef_AnnlRtrPct 14.97%
Annual Return [Percent] oef_AnnlRtrPct 7.41%
Annual Return [Percent] oef_AnnlRtrPct (17.30%)
Annual Return [Percent] oef_AnnlRtrPct 14.02%
Annual Return [Percent] oef_AnnlRtrPct 6.12%
Annual Return [Percent] oef_AnnlRtrPct 27.54%
MFS International Diversification Fund | Class A | After Taxes on Distributions  
Risk/Return: oef_RiskReturnAbstract  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns After Taxes on Distributions
Average Annual Return, Percent oef_AvgAnnlRtrPct 18.93%
Average Annual Return, Percent oef_AvgAnnlRtrPct 4.54%
Average Annual Return, Percent oef_AvgAnnlRtrPct 7.62%
MFS International Diversification Fund | Class A | After Taxes on Distributions and Sales  
Risk/Return: oef_RiskReturnAbstract  
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns After Taxes on Distributions and Sale of Fund Shares
Average Annual Return, Percent oef_AvgAnnlRtrPct 13.02%
Average Annual Return, Percent oef_AvgAnnlRtrPct 4.09%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.65%
MFS International Diversification Fund | Class B  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 4.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.83%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.82%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 585 [3]
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 875 [3]
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 1,189 [3]
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 1,950 [3]
Expense Example, No Redemption, 1 Year oef_ExpenseExampleNoRedemptionYear01 185 [3]
Expense Example, No Redemption, 3 Years oef_ExpenseExampleNoRedemptionYear03 575 [3]
Expense Example, No Redemption, 5 Years oef_ExpenseExampleNoRedemptionYear05 989 [3]
Expense Example, No Redemption, 10 Years oef_ExpenseExampleNoRedemptionYear10 $ 1,950 [3]
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 22.55%
Average Annual Return, Percent oef_AvgAnnlRtrPct 5.39%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.19%
MFS International Diversification Fund | Class C  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIGX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 1.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.83%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.82%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 285 [3]
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 575 [3]
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 989 [3]
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 1,950 [3]
Expense Example, No Redemption, 1 Year oef_ExpenseExampleNoRedemptionYear01 185 [3]
Expense Example, No Redemption, 3 Years oef_ExpenseExampleNoRedemptionYear03 575 [3]
Expense Example, No Redemption, 5 Years oef_ExpenseExampleNoRedemptionYear05 989 [3]
Expense Example, No Redemption, 10 Years oef_ExpenseExampleNoRedemptionYear10 $ 1,950 [3]
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 25.55%
Average Annual Return, Percent oef_AvgAnnlRtrPct 5.71%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.19%
MFS International Diversification Fund | Class I  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIJX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 0.83%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 0.82%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 264
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 460
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 1,024
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 27.81%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.78%
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.12%
MFS International Diversification Fund | Class R1  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIOX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.83%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.82%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 185
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 575
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 989
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 2,147
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 26.56%
Average Annual Return, Percent oef_AvgAnnlRtrPct 5.72%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.03%
MFS International Diversification Fund | Class R2  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIKX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.33%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.32%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 134
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 420
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 728
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 1,601
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 27.23%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.25%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.58%
MFS International Diversification Fund | Class R3  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIHX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 1.08%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 1.07%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 109
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 342
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 595
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 1,316
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 27.54%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.52%
Average Annual Return, Percent oef_AvgAnnlRtrPct 8.85%
MFS International Diversification Fund | Class R4  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDITX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.11%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 0.83%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 0.82%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 84
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 264
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 460
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 1,024
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 27.87%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.78%
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.12%
MFS International Diversification Fund | Class R6  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol MDIZX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) oef_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 0.00%
Maximum Deferred Sales Charge (as a percentage of Offering Price) oef_MaximumDeferredSalesChargeOverOfferingPrice 0.00%
Management Fees (as a percentage of Assets) oef_ManagementFeesOverAssets 0.00%
Distribution and Service (12b-1) Fees oef_DistributionAndService12b1FeesOverAssets 0.00%
Other Expenses (as a percentage of Assets): oef_OtherExpensesOverAssets 0.01%
Acquired Fund Fees and Expenses oef_AcquiredFundFeesAndExpensesOverAssets 0.72%
Expenses (as a percentage of Assets) oef_ExpensesOverAssets 0.73%
Fee Waiver or Reimbursement oef_FeeWaiverOrReimbursementOverAssets (0.01%) [2]
Net Expenses (as a percentage of Assets) oef_NetExpensesOverAssets 0.72%
Fee Waiver or Reimbursement over Assets, Date of Termination oef_FeeWaiverOrReimbursementOverAssetsDateOfTermination September 30, 2027
Expense Example, with Redemption, 1 Year oef_ExpenseExampleYear01 $ 74
Expense Example, with Redemption, 3 Years oef_ExpenseExampleYear03 232
Expense Example, with Redemption, 5 Years oef_ExpenseExampleYear05 405
Expense Example, with Redemption, 10 Years oef_ExpenseExampleYear10 $ 906
Average Annual Return, Label [Optional Text] oef_AverageAnnualReturnLabel Returns Before Taxes
Average Annual Return, Percent oef_AvgAnnlRtrPct 27.96%
Average Annual Return, Percent oef_AvgAnnlRtrPct 6.88%
Average Annual Return, Percent oef_AvgAnnlRtrPct 9.21%
[1] This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.
[2] Massachusetts Financial Services Company (MFS) has agreed in writing to bear the fund's expenses, excluding management fees, distribution and service fees, interest, taxes, extraordinary expenses, brokerage and transaction costs, investment-related expenses, and fees and expenses associated with investments in investment companies and other similar investment vehicles, such that "Other Expenses" do not exceed 0.10% of the class' average daily net assets annually for each of Class A, Class B, Class C, Class I, Class R1, Class R2, Class R3, and Class R4 shares, and 0.00% of the class' average daily net assets annually for Class R6 shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least September 30, 2027.
[3] Shares automatically convert to Class A shares approximately eight years after purchase; therefore, the expense examples reflect Class A share expenses after eight years.