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MFS® Global Real Estate Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MFS® Global Real Estate 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.
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 and hold shares of the fund. Expenses have been adjusted to reflect current fee arrangements.


You may qualify for sales charge reductions if 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 or Reductions” on page 8 of the fund’s Prospectus and “Waivers of Sales Charges” on page H-1 of the fund’s Statement of Additional Information (“SAI”).
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):
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination Dec. 31, 2016
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.  For the period March 1, 2015 through August 31, 2015, the fund’s portfolio turnover rate was 14% of the average value of its portfolio. Effective March 1, 2015, the fund changed its fiscal year end from February 28 to August 31.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 14.00%
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge reductions if 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] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expenses Restated to Reflect Current [Text] rr_ExpensesRestatedToReflectCurrent Expenses have been adjusted to reflect current fee arrangements.
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.
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 U.S. and foreign real estate-related investments.


MFS normally invests the fund’s assets primarily in equity securities.


MFS generally focuses the fund’s investments in equity real estate investment trusts (“REITs”) as well as similar entities formed under the laws of non-U.S. countries, but may also invest in mortgage REITs, hybrid REITs and other U.S. and foreign real estate-related investments, including emerging market real estate-related investments.


MFS may invest the fund’s assets in real estate-related investments of any size.  However, issuers of real estate-related investments tend to have small-to-medium market capitalizations.


MFS normally allocates the fund’s investments across different REIT managers and property types, but may from time to time focus the fund’s investments in any one or a few of these areas.


MFS normally allocates the fund’s investments across different countries and regions, but MFS may invest a large percentage of the fund’s assets in issuers in a single country, a small number of countries, or a particular geographic region.


MFS may invest a relatively large percentage of the fund’s assets in a single issuer or a small number of issuers.


MFS uses a bottom-up investment approach to buying and selling investments for the fund. Investments are selected primarily based on fundamental analysis of individual issuers.
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

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:


Real Estate-Related Investment Risk:  The fund’s performance will be closely tied to the performance of real estate-related investments and as a result, can be more volatile than the performance of more broadly-diversified funds. The risks of investing in real estate-related investments include certain risks associated with the direct ownership of real estate and the real estate industry in general. These include risks related to general, regional and local economic conditions; difficulties in valuing and disposing of real estate; fluctuations in interest rates and property tax rates; shifts in zoning laws, environmental regulations and other governmental action; cash flow dependency; increased operating expenses; lack of availability of mortgage funds; losses due to natural disasters; overbuilding; losses due to casualty or condemnation; changes in property values and rental rates; and other factors.


Small to Medium Cap Risk:  The securities of real estate-related issuers that have small to medium market capitalizations can be more volatile and less liquid than securities of larger issuers and such issuers can have more limited financial resources.


Stock Market/Company Risk:  Stock markets are volatile and can decline significantly in response to issuer, market, economic, industry, political, regulatory, geopolitical, and other conditions, as well as to investor perceptions of these conditions. The price of an equity security can decrease significantly in response to these conditions, and these conditions can affect a single issuer or type of security, issuers within a broad market sector, industry or geographic region, or the market in general.


Foreign Risk:  Exposure to foreign markets through issuers or currencies can involve additional risks relating to market, economic, industry, political, regulatory, geopolitical, and other conditions. These factors can make foreign investments, especially those in emerging markets, more volatile and less liquid than U.S. investments. In addition, foreign markets can react differently to these conditions than the U.S. market.


Emerging Markets Risk:  Investments in emerging markets can involve additional and greater risks than the risks associated with investments in developed foreign markets.  Emerging markets can have less developed markets, greater custody and operational risk, less developed legal, regulatory, and accounting systems, and greater political, social, and economic instability than developed markets.


Currency Risk:  The value of foreign currencies relative to the U.S. dollar fluctuates in response to market, economic, industry, political, regulatory, geopolitical, and other conditions, and a decline in the value of a foreign currency versus the U.S. dollar reduces the value in U.S. dollars of investments denominated in that foreign currency.


Geographic Focus Risk: The fund’s performance will be closely tied to the market, currency, economic, political, regulatory, geopolitical, and other conditions in the countries or regions in which the fund’s assets are invested.


Issuer Focus Risk:  The fund’s performance could be more volatile than the performance of more diversified funds.


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 a price or time that is not advantageous in order to meet redemptions or other cash needs.


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.
Risk Lose Money [Text] rr_RiskLoseMoney As with any mutual fund, the fund may not achieve its objective and/or you could lose money on your investment in the fund.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution 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.
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.


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] 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

The total return for the nine-month period ended September 30, 2015, was (3.83)%. During the period(s) shown in the bar chart, the highest quarterly return was 18.70% (for the calendar quarter ended September 30, 2010) and the lowest quarterly return was (18.05)% (for the calendar quarter ended September 30, 2011).

Year to Date Return, Label rr_YearToDateReturnLabel The total return for the nine-month period
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2015
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (3.83%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2010
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.70%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.05%)
Performance Table Heading rr_PerformanceTableHeading Performance Table.
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (Reflects no deduction for fees, expenses, or taxes)
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-deferred arrangements, such as 401(k) plans or individual retirement accounts.
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-deferred arrangements, such as 401(k) plans or individual retirement accounts. 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.
Caption rr_AverageAnnualReturnCaption Average Annual Total Returns (For the Periods Ended December 31, 2014)
MFS® Global Real Estate Fund | FTSE EPRA/NAREIT Developed Real Estate Index  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Index Comparison (Reflects no deduction for fees, expenses, or taxes) FTSE EPRA/NAREIT Developed Real Estate Index
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 15.89%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 12.03%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 24.14%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (Load) (as a percentage of original purchase price or redemption proceeds, whichever is less) rr_MaximumDeferredSalesChargeOverOther 1.00% [1]
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.44%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.35%
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.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 705
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 996
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,309
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,193
Annual Return 2010 rr_AnnualReturn2010 15.29%
Annual Return 2011 rr_AnnualReturn2011 (7.22%)
Annual Return 2012 rr_AnnualReturn2012 29.49%
Annual Return 2013 rr_AnnualReturn2013 4.74%
Annual Return 2014 rr_AnnualReturn2014 14.96%
Label rr_AverageAnnualReturnLabel A Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 8.35%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 9.47%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 21.31%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | A | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel A Shares Returns After Taxes on Distributions
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 6.92%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 6.98%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 16.95%
MFS® Global Real Estate Fund | A | After Taxes on Distributions and Sale of Fund Shares  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel A Shares Returns After Taxes on Distributions and Sale of Fund Shares
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 5.19%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 6.65%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 15.72%
MFS® Global Real Estate Fund | B  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther 4.00%
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.19%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 2.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 613
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 977
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,366
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,327
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 213
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 677
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,166
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,327
Label rr_AverageAnnualReturnLabel B Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 10.17%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 9.68%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 21.58%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | C  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther 1.00%
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.19%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 2.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 313
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 677
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,166
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,517
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 213
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 677
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,166
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,517
Label rr_AverageAnnualReturnLabel C Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 13.17%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 9.95%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 21.64%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | I  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.19%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 369
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 646
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,435
Label rr_AverageAnnualReturnLabel I Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 15.23%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 11.04%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 22.84%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | R1  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.19%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 2.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 213
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 677
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,166
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,517
Label rr_AverageAnnualReturnLabel R1 Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 14.17%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 9.95%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 21.64%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | R2  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.69%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.60%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 163
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 524
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 909
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,990
Label rr_AverageAnnualReturnLabel R2 Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 14.71%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 10.50%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 22.25%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | R3  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.44%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.35%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 137
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 447
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 778
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,716
Label rr_AverageAnnualReturnLabel R3 Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 14.99%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 10.77%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 22.55%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | R4  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.29%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.19%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.09%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.10%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 112
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 369
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 646
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,435
Label rr_AverageAnnualReturnLabel R4 Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 15.26%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 11.05%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 22.85%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
MFS® Global Real Estate Fund | R5  
Risk/Return: rr_RiskReturnAbstract  
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_MaximumDeferredSalesChargeOverOther none
Management Fee rr_ManagementFeesOverAssets 0.90%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.28%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.18%
Fee Reductions and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.13%) [2]
Total Annual Fund Operating Expenses After Fee Reductions and/or Expense Reimbursements rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 362
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 636
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,420
Label rr_AverageAnnualReturnLabel R5 Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 15.23%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 11.04%
Average Annual Returns, Since Inception rr_AverageAnnualReturnSinceInception 22.84%
Average Annual Returns, Inception Date rr_AverageAnnualReturnInceptionDate Mar. 11, 2009
[1] This contingent deferred sales charge (CDSC) applies to shares purchased without an initial sales charge and redeemed within 18 months of purchase.
[2] Effective January 1, 2016, Massachusetts Financial Services Company has agreed in writing to bear the fund's expenses, excluding interest, taxes, extraordinary expenses, brokerage and transaction costs, and investment-related expenses (such as interest and borrowing expenses incurred in connection with the fund's investment activity), such that "Total Annual Fund Operating Expenses" do not exceed 1.35% of the fund's average daily net assets annually for each of Class A and Class R3 shares, 2.10% of the fund's average daily net assets annually for each of Class B, Class C, and Class R1 shares, 1.10% of the fund's average daily net assets annually for each of Class I and Class R4 shares, 1.60% of the fund's average daily net assets annually for Class R2 shares, and 1.05% of the fund's average daily net assets annually for Class R5 shares. This written agreement will continue until modified by the fund's Board of Trustees, but such agreement will continue until at least December 31, 2016.