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    <rr:RiskReturnHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Fund Summary
                  Fund:Fidelity&#xae; Total International Index Fund

</rr:RiskReturnHeading>
    <rr:ObjectiveHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Investment Objective

</rr:ObjectiveHeading>
    <rr:ObjectivePrimaryTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         The fund seeks to provide investment results that correspond to the total return of foreign developed and emerging stock markets.

</rr:ObjectivePrimaryTextBlock>
    <rr:ExpenseHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Fee Table

</rr:ExpenseHeading>
    <rr:ExpenseNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund.

</rr:ExpenseNarrativeTextBlock>
    <rr:ShareholderFeesCaption contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Shareholder fees

</rr:ShareholderFeesCaption>
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      decimals="0"
      unitRef="usd">0</rr:ShareholderFeeOther>
    <rr:OperatingExpensesCaption contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Annual Operating Expenses
                  (expenses that you pay each year as a % of the value of your investment)

</rr:OperatingExpensesCaption>
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      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
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      unitRef="pure">0.0006</rr:ManagementFeesOverAssets>
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      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
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      unitRef="pure">0</rr:DistributionAndService12b1FeesOverAssets>
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      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
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    <rr:ExpensesOverAssets
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
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    <rr:ExpenseExampleNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         This example helps compare the cost of investing in the fund with the cost of investing in other funds.

                  Let's say, hypothetically, that the annual return for shares of the fund is 5% and that your shareholder fees and the annual
            operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses
            or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end
            of each time period indicated:


</rr:ExpenseExampleNarrativeTextBlock>
    <rr:ExpenseExampleYear01
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="0"
      unitRef="usd">6</rr:ExpenseExampleYear01>
    <rr:ExpenseExampleYear03
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="0"
      unitRef="usd">19</rr:ExpenseExampleYear03>
    <rr:ExpenseExampleYear05
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="0"
      unitRef="usd">34</rr:ExpenseExampleYear05>
    <rr:ExpenseExampleYear10
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="0"
      unitRef="usd">77</rr:ExpenseExampleYear10>
    <rr:PortfolioTurnoverHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">Portfolio Turnover

</rr:PortfolioTurnoverHeading>
    <rr:PortfolioTurnoverTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         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 fund shares are
            held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was 5% of the average value of its portfolio.


</rr:PortfolioTurnoverTextBlock>
    <rr:PortfolioTurnoverRate
      contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="4"
      unitRef="pure">0.05</rr:PortfolioTurnoverRate>
    <rr:StrategyHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Principal Investment Strategies

</rr:StrategyHeading>
    <rr:StrategyNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">
            Normally investing at least 80% of assets in securities included in the MSCI ACWI (All Country World Index) ex USA Investable
               Market Index and in depositary receipts representing securities included in the index. The MSCI ACWI (All Country World Index)
               ex USA Investable Market Index is a market capitalization-weighted index designed to measure the investable equity market
               performance for global investors of large, mid, and small-cap stocks in developed and emerging markets, excluding the U.S.



            Using statistical sampling techniques based on such factors as capitalization, industry exposures, dividend yield, price/earnings
               (P/E) ratio, price/book (P/B) ratio, earnings growth, country weightings, and the effect of foreign taxes to attempt to replicate
               the returns of the MSCI ACWI (All Country World Index) ex USA Investable Market Index.



            Lending securities to earn income for the fund.


</rr:StrategyNarrativeTextBlock>
    <rr:RiskHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Principal Investment Risks

</rr:RiskHeading>
    <rr:RiskNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">
            Stock Market Volatility.&#160;Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or
               economic developments. Different parts of the market, including different market sectors, and different types of securities
               can react differently to these developments.



            Foreign and Emerging Market Risk.&#160;Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse
               issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory
               oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and
               financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information
               available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties
               and can be extremely volatile. Foreign exchange rates also can be extremely volatile.



            Issuer-Specific Changes.&#160;The value of an individual security or particular type of security can be more volatile than, and can perform differently
               from, the market as a whole. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending
               transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's
               value or result in delays in recovering securities and/or capital from a counterparty.



            Correlation to Index.&#160;The performance of the fund and its underlying index may vary somewhat due to factors such as fees and expenses of the fund,
               transaction costs, sample selection, regulatory restrictions, and timing differences associated with additions to and deletions
               from the index. Errors in the construction or calculation of the index may occur from time to time and may not be identified
               and corrected for some period of time, which may have an adverse impact on the fund and its shareholders.



            Passive Management Risk.&#160;The fund is managed with a passive investment strategy, attempting to track the performance of an unmanaged index of securities,
               regardless of the current or projected performance of the fund&#x92;s index or of the actual securities included in the index.
               This differs from an actively managed fund, which typically seeks to outperform a benchmark index. As a result, the fund&#x92;s
               performance could be lower than actively managed funds that may shift their portfolio assets to take advantage of market opportunities
               or lessen the impact of a market decline or a decline in the value of one or more issuers.



            Mid Cap Investing.&#160;The value of securities of medium size, less well-known issuers can perform differently from the market as a whole and other
               types of stocks and can be more volatile than that of larger issuers.



            Small Cap Investing.&#160;The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types
               of stocks and can be more volatile than that of larger issuers.



            Securities Lending Risk.&#160;Securities lending involves the risk that the borrower may fail to return the securities loaned in a timely manner or at all.
               If the borrower defaults on its obligation to return the securities loaned because of insolvency or other reasons, a fund
               could experience delays and costs in recovering the securities loaned or in gaining access to the collateral.


                  An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation
               or any other government agency. You could lose money by investing in the fund.


</rr:RiskNarrativeTextBlock>
    <rr:RiskNotInsuredDepositoryInstitution contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation
               or any other government agency.</rr:RiskNotInsuredDepositoryInstitution>
    <rr:RiskLoseMoney contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">You could lose money by investing in the fund.</rr:RiskLoseMoney>
    <rr:BarChartAndPerformanceTableHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Performance

</rr:BarChartAndPerformanceTableHeading>
    <rr:PerformanceNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">                  The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance
               of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance (before and after taxes) is not an indication of future performance.

                  Visit www.fidelity.com for more recent performance information.


</rr:PerformanceNarrativeTextBlock>
    <rr:PerformanceInformationIllustratesVariabilityOfReturns contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance
               of the fund's shares to the performance of a securities market index over various periods of time.</rr:PerformanceInformationIllustratesVariabilityOfReturns>
    <rr:PerformancePastDoesNotIndicateFuture contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">Past performance (before and after taxes) is not an indication of future performance.</rr:PerformancePastDoesNotIndicateFuture>
    <rr:PerformanceAvailabilityWebSiteAddress contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">www.fidelity.com</rr:PerformanceAvailabilityWebSiteAddress>
    <rr:BarChartHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         Year-by-Year Returns

</rr:BarChartHeading>
    <rr:HighestQuarterlyReturnLabel contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member">Highest Quarter Return</rr:HighestQuarterlyReturnLabel>
    <rr:BarChartHighestQuarterlyReturn
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      decimals="4"
      unitRef="pure">0.1741</rr:BarChartHighestQuarterlyReturn>
    <rr:BarChartHighestQuarterlyReturnDate contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member">2020-06-30</rr:BarChartHighestQuarterlyReturnDate>
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    <rr:BarChartLowestQuarterlyReturn
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="4"
      unitRef="pure">-0.2415</rr:BarChartLowestQuarterlyReturn>
    <rr:BarChartLowestQuarterlyReturnDate contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member">2020-03-31</rr:BarChartLowestQuarterlyReturnDate>
    <rr:YearToDateReturnLabel contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member">Year-to-Date Return</rr:YearToDateReturnLabel>
    <rr:BarChartYearToDateReturn
      contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="4"
      unitRef="pure">0.0634</rr:BarChartYearToDateReturn>
    <rr:BarChartYearToDateReturnDate contextRef="S000054097_C000170041_D1031FidelityTotalInternationalIndexFundPRO13Member">2021-09-30</rr:BarChartYearToDateReturnDate>
    <rr:PerformanceTableHeading contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">Average Annual Returns

</rr:PerformanceTableHeading>
    <rr:PerformanceTableNarrativeTextBlock contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">         After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect
               the impact of state or local taxes. Actual after-tax returns may differ depending on your individual circumstances. The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement,
               such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan). Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a
               tax benefit of realizing a capital loss upon the sale of fund shares.


</rr:PerformanceTableNarrativeTextBlock>
    <rr:PerformanceTableUsesHighestFederalRate contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect
               the impact of state or local taxes.</rr:PerformanceTableUsesHighestFederalRate>
    <rr:PerformanceTableNotRelevantToTaxDeferred contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement,
               such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).</rr:PerformanceTableNotRelevantToTaxDeferred>
    <rr:PerformanceTableExplanationAfterTaxHigher contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a
               tax benefit of realizing a capital loss upon the sale of fund shares.</rr:PerformanceTableExplanationAfterTaxHigher>
    <rr:AverageAnnualReturnLabel contextRef="S000054097_C000170041_ReturnBeforeTaxes_D1031FidelityTotalInternationalIndexFundPRO13Member">Return Before Taxes</rr:AverageAnnualReturnLabel>
    <rr:AverageAnnualReturnYear01
      contextRef="S000054097_C000170041_ReturnBeforeTaxes_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="4"
      unitRef="pure">0.1107</rr:AverageAnnualReturnYear01>
    <rr:AverageAnnualReturnSinceInception
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      unitRef="pure">0.0898</rr:AverageAnnualReturnSinceInception>
    <rr:AverageAnnualReturnLabel contextRef="S000054097_C000170041_AfterTaxesOnDistributions_D1031FidelityTotalInternationalIndexFundPRO13Member">Return After Taxes on Distributions</rr:AverageAnnualReturnLabel>
    <rr:AverageAnnualReturnYear01
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      unitRef="pure">0.1077</rr:AverageAnnualReturnYear01>
    <rr:AverageAnnualReturnSinceInception
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      unitRef="pure">0.0854</rr:AverageAnnualReturnSinceInception>
    <rr:AverageAnnualReturnLabel contextRef="S000054097_C000170041_AfterTaxesOnDistributionsAndSales_D1031FidelityTotalInternationalIndexFundPRO13Member">Return After Taxes on Distributions and Sale of Fund Shares</rr:AverageAnnualReturnLabel>
    <rr:AverageAnnualReturnYear01
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      unitRef="pure">0.0697</rr:AverageAnnualReturnYear01>
    <rr:AverageAnnualReturnSinceInception
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      unitRef="pure">0.0707</rr:AverageAnnualReturnSinceInception>
    <rr:AverageAnnualReturnLabel contextRef="S000054097_IndexIX425_D1031FidelityTotalInternationalIndexFundPRO13Member">MSCI ACWI (All Country World Index) ex USA Investable Market Index</rr:AverageAnnualReturnLabel>
    <rr:AverageAnnualReturnYear01
      contextRef="S000054097_IndexIX425_D1031FidelityTotalInternationalIndexFundPRO13Member"
      decimals="4"
      unitRef="pure">0.1128</rr:AverageAnnualReturnYear01>
    <rr:AverageAnnualReturnSinceInception
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      unitRef="pure">0.0932</rr:AverageAnnualReturnSinceInception>
    <rr:AnnualReturnInceptionDate contextRef="S000054097_D1031FidelityTotalInternationalIndexFundPRO13Member">2016-06-07</rr:AnnualReturnInceptionDate>
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