v3.26.3
Investment Risks
Oct. 30, 2026
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government Income Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government 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 .
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government Income 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government Income Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government Income 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Government Income Fund | USGovernmentObligationsRiskMember  
Prospectus Line Items  
Risk [Text Block] U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government Income Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government 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 .
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government Income 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government Income Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government Income 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.
FidelityGovernmentBondFunds-RetailComboPRO | Fidelity Intermediate Government Income Fund | USGovernmentObligationsRiskMember  
Prospectus Line Items  
Risk [Text Block] U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond 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 .
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond 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.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond 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. Foreign exchange rates also can be extremely volatile.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond 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. Investments in covenant-lite loans carry more risk than traditional loans as they allow issuers to engage in activities that would otherwise be difficult or impossible under a traditional loan agreement. In the event of default, covenant-lite obligations have lower recovery values as the lender may not have the opportunity to negotiate with the borrower prior to default.
FidelityTotalBondFund-RetailPRO | Fidelity Total Bond 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.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond 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 .
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond 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.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond 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. Foreign exchange rates also can be extremely volatile.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond 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. Investments in covenant-lite loans carry more risk than traditional loans as they allow issuers to engage in activities that would otherwise be difficult or impossible under a traditional loan agreement. In the event of default, covenant-lite obligations have lower recovery values as the lender may not have the opportunity to negotiate with the borrower prior to default.
FidelityTotalBondFund-AMCIZPRO | Fidelity Total Bond 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.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government Bond Index Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government 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 .
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government 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.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government 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.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government 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 benchmark 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 benchmark index concentrates in the securities of issuers in a particular industry or group of industries.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government 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.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government Bond Index Fund | USGovernmentObligationsRiskMember  
Prospectus Line Items  
Risk [Text Block] U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.
FidelitySeriesGovernmentBondIndexFund-PRO | Fidelity Series Government Bond Index Fund | CorrelationToIndexMember  
Prospectus Line Items  
Risk [Text Block] Correlation to Index. The performance of the fund and its benchmark 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.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government Income Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government 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 .
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government 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.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government Income 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.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government Income Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government 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.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government Income 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.
FidelityGovernmentIncomeFund-AMCIZPRO | Fidelity Government Income Fund | USGovernmentObligationsRiskMember  
Prospectus Line Items  
Risk [Text Block] U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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 .
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond Fund | EnvironmentalFocusRiskMember  
Prospectus Line Items  
Risk [Text Block] Environmental Focus Risk. The fund normally invests in issuers whose products or services are intended or likely to have a positive environmental impact. Some industries and sectors might be more likely to issue environmental bonds, and events or factors impacting these sectors may have a greater effect on, and may more adversely affect, the fund than they would a fund that does not invest in issuers with a common purpose. The fund also will be affected by a decrease in governmental or other support for environmental initiatives.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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) 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 can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-RetailPRO | Fidelity Environmental Bond Fund | SustainabilityRiskMember  
Prospectus Line Items  
Risk [Text Block] Sustainability Risk. Application of Fidelity Management & Research Company LLC's (FMR) (the Adviser) environmental, social and governance (ESG) rating process and/or its sustainable investing exclusion criteria may affect the fund's exposure to certain issuers, sectors, regions, and countries and may affect the fund's performance depending on whether certain investments are in or out of favor. The criteria related to the fund's ESG rating process and/or adherence to its sustainable investing exclusion criteria may result in the fund forgoing opportunities to buy certain securities when it might otherwise be advantageous to do so, or selling securities for ESG reasons when it might be otherwise disadvantageous for it to do so. As a result, the fund's performance may at times be better or worse than the performance of funds that do not use ESG or sustainability criteria. There are significant differences in interpretations of what it means for an issuer to have positive ESG factors. While the Adviser believes its definitions are reasonable, the portfolio decisions it makes may differ with other investors' or advisers' views. When evaluating an issuer, the Adviser is dependent on information or data obtained through voluntary or third-party reporting that may be incomplete, inaccurate, or unavailable, which could cause the Adviser to incorrectly assess an issuer's business practices.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 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 .
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 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.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 Fund | HighPortfolioTurnoverMember  
Prospectus Line Items  
Risk [Text Block] High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 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. Foreign exchange rates also can be extremely volatile.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 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. Investments in covenant-lite loans carry more risk than traditional loans as they allow issuers to engage in activities that would otherwise be difficult or impossible under a traditional loan agreement. In the event of default, covenant-lite obligations have lower recovery values as the lender may not have the opportunity to negotiate with the borrower prior to default.
FidelityTotalBondK6Fund-PRO | Fidelity Total Bond K6 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.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond Fund | Risk Lose Money [Member]  
Prospectus Line Items  
Risk [Text Block]   You could lose money by investing in the fund.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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 .
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond Fund | InterestRateChangesMember  
Prospectus Line Items  
Risk [Text Block] Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond Fund | EnvironmentalFocusRiskMember  
Prospectus Line Items  
Risk [Text Block] Environmental Focus Risk. The fund normally invests in issuers whose products or services are intended or likely to have a positive environmental impact. Some industries and sectors might be more likely to issue environmental bonds, and events or factors impacting these sectors may have a greater effect on, and may more adversely affect, the fund than they would a fund that does not invest in issuers with a common purpose. The fund also will be affected by a decrease in governmental or other support for environmental initiatives.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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) 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 can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond 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.
FidelityEnvironmentalBondFund-AMCIZPRO | Fidelity Environmental Bond Fund | SustainabilityRiskMember  
Prospectus Line Items  
Risk [Text Block] Sustainability Risk. Application of Fidelity Management & Research Company LLC's (FMR) (the Adviser) environmental, social and governance (ESG) rating process and/or its sustainable investing exclusion criteria may affect the fund's exposure to certain issuers, sectors, regions, and countries and may affect the fund's performance depending on whether certain investments are in or out of favor. The criteria related to the fund's ESG rating process and/or adherence to its sustainable investing exclusion criteria may result in the fund forgoing opportunities to buy certain securities when it might otherwise be advantageous to do so, or selling securities for ESG reasons when it might be otherwise disadvantageous for it to do so. As a result, the fund's performance may at times be better or worse than the performance of funds that do not use ESG or sustainability criteria. There are significant differences in interpretations of what it means for an issuer to have positive ESG factors. While the Adviser believes its definitions are reasonable, the portfolio decisions it makes may differ with other investors' or advisers' views. When evaluating an issuer, the Adviser is dependent on information or data obtained through voluntary or third-party reporting that may be incomplete, inaccurate, or unavailable, which could cause the Adviser to incorrectly assess an issuer's business practices.
Document Type 485BPOS