v3.26.1
Investment Risks
Aug. 29, 2026
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | Risk Not Insured Depository Institution [Member]  
Prospectus Line Items  
Risk [Text Block] 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 .
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | QuantitativeInvestingMember  
Prospectus Line Items  
Risk [Text Block] Quantitative Investing. Securities selected using quantitative analysis can perform differently from the market as a whole as a result of the factors used in the analysis, the weight placed on each factor, and changes in the factors' historical trends.
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | IssuerSpecificChangesMember  
Prospectus Line Items  
Risk [Text Block] Issuer-Specific Changes. 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. A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.
FidelitySAIEnhancedMunicipalIncomeFund-PRO | Fidelity SAI Enhanced Municipal Income Fund | MunicipalMarketVolatilityMember  
Prospectus Line Items  
Risk [Text Block] Municipal Market Volatility. The municipal market is volatile and can be significantly affected by adverse tax, legislative, or political changes and the financial condition of the issuers of municipal securities.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | Risk Not Insured Depository Institution [Member]  
Prospectus Line Items  
Risk [Text Block] 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 .
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | GrowthInvestingMember  
Prospectus Line Items  
Risk [Text Block] "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.      
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | SecuritiesLendingRiskMember  
Prospectus Line Items  
Risk [Text Block] Securities Lending Risk. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | IssuerSpecificChangesMember  
Prospectus Line Items  
Risk [Text Block] Issuer-Specific Changes. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | StockMarketVolatilityMember  
Prospectus Line Items  
Risk [Text Block] Stock Market Volatility. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | PassiveManagementRiskMember  
Prospectus Line Items  
Risk [Text Block] Passive Management Risk. 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'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'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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | MidCapInvestingMember  
Prospectus Line Items  
Risk [Text Block] Mid Cap Investing. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Growth Index Fund | CorrelationToIndexMember  
Prospectus Line Items  
Risk [Text Block] Correlation to Index. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | Risk Not Insured Depository Institution [Member]  
Prospectus Line Items  
Risk [Text Block] 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 .
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | SecuritiesLendingRiskMember  
Prospectus Line Items  
Risk [Text Block] Securities Lending Risk. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | ValueInvestingMember  
Prospectus Line Items  
Risk [Text Block] "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | IssuerSpecificChangesMember  
Prospectus Line Items  
Risk [Text Block] Issuer-Specific Changes. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | StockMarketVolatilityMember  
Prospectus Line Items  
Risk [Text Block] Stock Market Volatility. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | PassiveManagementRiskMember  
Prospectus Line Items  
Risk [Text Block] Passive Management Risk. 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'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'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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | MidCapInvestingMember  
Prospectus Line Items  
Risk [Text Block] Mid Cap Investing. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Mid Cap Value Index Fund | CorrelationToIndexMember  
Prospectus Line Items  
Risk [Text Block] Correlation to Index. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | Risk Not Insured Depository Institution [Member]  
Prospectus Line Items  
Risk [Text Block] 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 .
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | GrowthInvestingMember  
Prospectus Line Items  
Risk [Text Block] "Growth" Investing. "Growth" stocks can perform differently from the market as a whole and other types of stocks and can be more volatile than other types of stocks.      
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | SecuritiesLendingRiskMember  
Prospectus Line Items  
Risk [Text Block] Securities Lending Risk. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | IssuerSpecificChangesMember  
Prospectus Line Items  
Risk [Text Block] Issuer-Specific Changes. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | StockMarketVolatilityMember  
Prospectus Line Items  
Risk [Text Block] Stock Market Volatility. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | PassiveManagementRiskMember  
Prospectus Line Items  
Risk [Text Block] Passive Management Risk. 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'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'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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | SmallCapInvestingMember  
Prospectus Line Items  
Risk [Text Block] Small Cap Investing. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Growth Index Fund | CorrelationToIndexMember  
Prospectus Line Items  
Risk [Text Block] Correlation to Index. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | Risk Not Insured Depository Institution [Member]  
Prospectus Line Items  
Risk [Text Block] 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 .
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | SecuritiesLendingRiskMember  
Prospectus Line Items  
Risk [Text Block] Securities Lending Risk. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | ValueInvestingMember  
Prospectus Line Items  
Risk [Text Block] "Value" Investing. "Value" stocks can perform differently from the market as a whole and other types of stocks and can continue to be undervalued by the market for long periods of time.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | IssuerSpecificChangesMember  
Prospectus Line Items  
Risk [Text Block] Issuer-Specific Changes. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | StockMarketVolatilityMember  
Prospectus Line Items  
Risk [Text Block] Stock Market Volatility. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | PassiveManagementRiskMember  
Prospectus Line Items  
Risk [Text Block] Passive Management Risk. 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'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'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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | SmallCapInvestingMember  
Prospectus Line Items  
Risk [Text Block] Small Cap Investing. 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.
FidelityMidCapGrowthMidCapValueSmallCapGrowthSmallCapValueIndexFunds-ComboPRO | Fidelity Small Cap Value Index Fund | CorrelationToIndexMember  
Prospectus Line Items  
Risk [Text Block] Correlation to Index. 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.
Document Type 485BPOS