Investment Risks	Feb. 28, 2026
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond 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 .
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond 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. 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.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond 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.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond Index Fund | USTreasuryObligationsMember
Prospectus Line Items
Risk [Text Block]	U.S. Treasury Obligations. U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond Index Fund | InvestingForInflationProtectionMember
Prospectus Line Items
Risk [Text Block]	Investing for Inflation Protection. Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.
FidelitySAIInflation-ProtectedBondIndexFund-PRO | Fidelity SAI Inflation-Protected Bond 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.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | Risk Nondiversified Status [Member]
Prospectus Line Items
Risk [Text Block]	In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond 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 .
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond 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. 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.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond 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.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | ForeignCurrencyTransactionsMember
Prospectus Line Items
Risk [Text Block]	Foreign Currency Transactions. Although a forward foreign currency exchange contract is used to reduce or hedge a fund's exposure to changes in the value of the currency, suitable hedging transactions may not be available in all circumstances, may not be successful, and may eliminate any chance for the fund to benefit from favorable fluctuations in relevant foreign currencies.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | ForeignExposureMember
Prospectus Line Items
Risk [Text Block]	Foreign Exposure. Foreign 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. Foreign exchange rates also can be extremely volatile.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond 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. The fund will be concentrated to approximately the same extent that the fund's index concentrates in the securities of issuers in a particular industry.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | PrepaymentMember
Prospectus Line Items
Risk [Text Block]	Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
FidelityInternationalBondIndexFund-PRO | Fidelity International Bond Index Fund | GeographicExposureToEuropeMember
Prospectus Line Items
Risk [Text Block]	Geographic Exposure to Europe. Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond 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 .
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond 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. 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.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond 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.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond Index Fund | USTreasuryObligationsMember
Prospectus Line Items
Risk [Text Block]	U.S. Treasury Obligations. U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond Index Fund | InvestingForInflationProtectionMember
Prospectus Line Items
Risk [Text Block]	Investing for Inflation Protection. Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.
FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PRO | Fidelity SAI 0-5 Year Inflation-Protected Bond 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond 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 .
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond 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. 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond Index Fund | USTreasuryObligationsMember
Prospectus Line Items
Risk [Text Block]	U.S. Treasury Obligations. U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond Index Fund | InvestingForInflationProtectionMember
Prospectus Line Items
Risk [Text Block]	Investing for Inflation Protection. Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 0-5 Year Inflation-Protected Bond 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond 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 .
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond 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. 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond 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.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond Index Fund | USTreasuryObligationsMember
Prospectus Line Items
Risk [Text Block]	U.S. Treasury Obligations. U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond Index Fund | InvestingForInflationProtectionMember
Prospectus Line Items
Risk [Text Block]	Investing for Inflation Protection. Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.
FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPRO | Fidelity Series 5+ Year Inflation-Protected Bond 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.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit 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 .
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | ContingentConvertibleSecuritiesRiskMember
Prospectus Line Items
Risk [Text Block]	Contingent Convertible Securities Risk. Contingent convertible securities have unique equity conversion or principal write-down features that involve additional risks, which may include cancellation of interest payments by the issuer or a regulatory authority; subordination to other creditors due to either a liquidation or other bankruptcy-related event or a conversion of the security from debt to equity; and a write-down of the security's principal amount.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit 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. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | ForeignCurrencyTransactionsMember
Prospectus Line Items
Risk [Text Block]	Foreign Currency Transactions. Although a forward foreign currency exchange contract is used to reduce or hedge a fund's exposure to changes in the value of the currency, suitable hedging transactions may not be available in all circumstances, may not be successful, and may eliminate any chance for the fund to benefit from favorable fluctuations in relevant foreign currencies.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | ForeignExposureMember
Prospectus Line Items
Risk [Text Block]	Foreign Exposure. 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.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | PrepaymentMember
Prospectus Line Items
Risk [Text Block]	Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.
FidelitySAIInternationalCreditFund-PRO | Fidelity SAI International Credit Fund | GeographicExposureToEuropeMember
Prospectus Line Items
Risk [Text Block]	Geographic Exposure to Europe. Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds.
FidelitySAIMunicipalIncomeFund-PRO | Fidelity SAI Municipal Income Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelitySAIMunicipalIncomeFund-PRO | Fidelity SAI 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 .
FidelitySAIMunicipalIncomeFund-PRO | Fidelity SAI 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.
FidelitySAIMunicipalIncomeFund-PRO | Fidelity SAI 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.
FidelitySAIMunicipalIncomeFund-PRO | Fidelity SAI 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.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond Index Fund | Risk Lose Money [Member]
Prospectus Line Items
Risk [Text Block]	You could lose money by investing in the fund.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond 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 .
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond Index Fund | LeverageRiskMember
Prospectus Line Items
Risk [Text Block]	Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond 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. 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.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond 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.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond Index Fund | InterestRateChangesMember
Prospectus Line Items
Risk [Text Block]	Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond Index Fund | USTreasuryObligationsMember
Prospectus Line Items
Risk [Text Block]	U.S. Treasury Obligations. U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond Index Fund | InvestingForInflationProtectionMember
Prospectus Line Items
Risk [Text Block]	Investing for Inflation Protection. Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.
FidelityInflation-ProtectedBondIndexFund-PRO | Fidelity Inflation-Protected Bond 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.
Document Type	485BPOS