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Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading MFS Virginia Municipal 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 income exempt from federal income tax and personal income tax, if any, of Virginia, but also considering capital appreciation.

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.


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 I-29 of the fund’s statement of additional information Part I.

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 11% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 11.00%
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
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

The fund invests, under normal market conditions, at least 80% of its net assets in securities and other investments, the interest on which is exempt from federal income tax and personal income tax, if any, of Virginia. Interest from the fund’s investments may be subject to the federal alternative minimum tax.


MFS (Massachusetts Financial Services Company, the fund’s investment adviser) normally invests the fund’s assets primarily in municipal instruments.


MFS may invest 25% or more of the fund’s assets in municipal instruments that finance similar projects, such as those relating to education, healthcare, housing, utilities, water or sewers. Municipal instruments whose interest is exempt from federal and state personal income tax include instruments issued by U.S. territories and possessions (such as Puerto Rico, Guam, and the U.S. Virgin Islands) and their political subdivisions and public corporations. Although MFS seeks to invest the fund’s assets in municipal instruments whose interest is exempt from federal and state personal income tax, MFS may also invest in taxable instruments.


MFS primarily invests the fund’s assets in investment grade debt instruments, but may also invest in less than investment grade quality debt instruments (lower quality debt instruments).


MFS invests a large percentage of the fund’s assets in municipal issuers of Virginia.


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 exposure, or as alternatives to direct investments. Derivatives include futures, forward contracts, options, structured securities, inverse floating rate instruments, and swaps.


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 instruments and their issuers. Quantitative models that systematically evaluate instruments may also be considered. In structuring the fund, MFS may also consider top-down factors.

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:


Interest Rate Risk:  The price of a debt instrument falls when interest rates rise and rises when interest rates fall. Instruments with longer maturities, or that do not pay current interest, are more sensitive to interest rate changes.


Credit Risk:  The price of a debt instrument depends, in part, on the credit quality of the issuer, borrower, counterparty, or underlying collateral or assets and the terms of the instrument. The price of a debt instrument can decline in response to changes in the financial condition of the issuer, borrower, counterparty, or underlying collateral or assets, or changes in specific or general market, economic, industry, political, regulatory, geopolitical, and other conditions.


The credit quality of, and the ability to pay principal and interest when due by, an issuer of a municipal instrument depends on the credit quality of the entity supporting the municipal instrument, how essential any services supported by the municipal instrument are, the sufficiency of any revenues or taxes that support the municipal instrument, and/or the willingness or ability of the appropriate government entity to approve any appropriations necessary to support the municipal instrument.


Lower 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. Lower quality debt instruments are regarded as having predominantly speculative characteristics. Lower 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.


Geographic Focus Risk:  The fund’s performance will be closely tied to the economic and political conditions in Virginia, and can be more volatile than the performance of a more geographically diversified fund. In addition, the fund’s performance can also be tied to the economic and political conditions of U.S. territories and possessions. These conditions may include constitutional or statutory limits on an issuer’s ability to raise revenues or increase taxes, anticipated or actual budget deficits or other financial difficulties, or changes in the credit quality of municipal issuers in the state or in U.S. territories and possessions.


Municipal Risk:  The price of a municipal instrument can be volatile and significantly affected by adverse tax or court rulings, legislative or political changes, changes in specific or general market and economic conditions, and the financial condition of municipal issuers and insurers. Because many municipal instruments are issued to finance similar projects, conditions in these industries can significantly affect the fund and the overall municipal market.


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.


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.


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


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.


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 to perform in accordance with the terms of the transaction.


Liquidity Risk:  It may not be possible to sell certain investments, types of investments, and/or segments of the market at any particular time or at an acceptable price.

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 six-month period ended June 30, 2013, was (3.68)%.  During the period(s) shown in the bar chart, the highest quarterly return was 6.69% (for the calendar quarter ended September 30, 2009) and the lowest quarterly return was (4.48)% (for the calendar quarter ended December 31, 2010).

Year to Date Return, Label rr_YearToDateReturnLabel The total return for the six-month period ended
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Jun. 30, 2013
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (3.68%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest quarterly return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 6.69%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest quarterly return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2010
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (4.48%)
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, 2012)
Barclays Municipal Bond Index
  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Index Comparison (Reflects no deduction for fees, expenses or taxes) Barclays Municipal Bond Index
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 6.78%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 5.91%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 5.10%
A
  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.75%
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 0.45%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.86%
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012.
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 559
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 736
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 929
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,485
Annual Return 2003 rr_AnnualReturn2003 5.36%
Annual Return 2004 rr_AnnualReturn2004 4.23%
Annual Return 2005 rr_AnnualReturn2005 3.35%
Annual Return 2006 rr_AnnualReturn2006 4.03%
Annual Return 2007 rr_AnnualReturn2007 2.80%
Annual Return 2008 rr_AnnualReturn2008 (5.47%)
Annual Return 2009 rr_AnnualReturn2009 15.88%
Annual Return 2010 rr_AnnualReturn2010 0.51%
Annual Return 2011 rr_AnnualReturn2011 9.70%
Annual Return 2012 rr_AnnualReturn2012 7.17%
Label rr_AverageAnnualReturnLabel A Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 2.08%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 4.28%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 4.11%
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 2.08%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 4.23%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 4.09%
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 2.57%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 4.21%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 4.10%
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 0.45%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 564
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 808
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,076
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,710
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 164
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 508
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 876
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 1,710
Label rr_AverageAnnualReturnLabel B Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 2.38%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 4.18%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 4.07%
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 0.45%
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.61%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 264
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 508
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 876
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,911
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 164
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 508
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 876
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,911
Label rr_AverageAnnualReturnLabel C Shares Returns Before Taxes
Average Annual Returns, 1 Year rr_AverageAnnualReturnYear01 5.47%
Average Annual Returns, 5 Years rr_AverageAnnualReturnYear05 4.53%
Average Annual Returns, 10 Years rr_AverageAnnualReturnYear10 3.90%
[1] On shares purchased without an initial sales charge and redeemed within 18 months of purchase for shares purchased on or after August 1, 2012, and within 24 months of purchase for shares purchased prior to August 1, 2012.