v3.25.3
Shareholder Report, Holdings (Details)
Aug. 31, 2025
Fidelity Total Bond K6 Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 25.70%
Fidelity Total Bond K6 Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Total Bond K6 Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Total Bond K6 Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Total Bond K6 Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.30%
Fidelity Total Bond K6 Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity Total Bond K6 Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Total Bond K6 Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Total Bond K6 Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Total Bond K6 Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Total Bond K6 Fund | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 57.40%
Fidelity Total Bond K6 Fund | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.10%
Fidelity Total Bond K6 Fund | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Total Bond K6 Fund | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.70%
Fidelity Total Bond K6 Fund | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Total Bond K6 Fund | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Total Bond K6 Fund | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.40%
Fidelity Total Bond K6 Fund | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Total Bond K6 Fund | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond K6 Fund | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
Fidelity Total Bond K6 Fund | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond K6 Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.70%
Fidelity Total Bond K6 Fund | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.30%
Fidelity Total Bond K6 Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Total Bond K6 Fund | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Total Bond K6 Fund | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Total Bond K6 Fund | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Total Bond K6 Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Total Bond K6 Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Total Bond K6 Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Total Bond K6 Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity Total Bond K6 Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 36.70%
Fidelity Total Bond K6 Fund | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.00%
Fidelity Total Bond K6 Fund | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.70%
Fidelity Total Bond K6 Fund | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.60%
Fidelity Total Bond K6 Fund | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Total Bond K6 Fund | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.30%
Fidelity Total Bond K6 Fund | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Total Bond K6 Fund | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Total Bond K6 Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond K6 Fund | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond K6 Fund | AAAlternativeFundsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond K6 Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond K6 Fund | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Total Bond Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Total Bond Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Total Bond Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Total Bond Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Total Bond Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Total Bond Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Total Bond Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Total Bond Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Total Bond Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Total Bond Fund | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Total Bond Fund | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Total Bond Fund | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Total Bond Fund | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Total Bond Fund | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Total Bond Fund | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Total Bond Fund | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Total Bond Fund | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Total Bond Fund | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond Fund | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Total Bond Fund | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Total Bond Fund | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Total Bond Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Total Bond Fund | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Total Bond Fund | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Total Bond Fund | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Total Bond Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Total Bond Fund | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Total Bond Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Total Bond Fund | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Total Bond Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Total Bond Fund | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Total Bond Fund | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Total Bond Fund | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Total Bond Fund | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Total Bond Fund | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Total Bond Fund | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Total Bond Fund | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Total Bond Fund | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond Fund | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond Fund | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond Fund | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class Z | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Advisor Total Bond Fund - Class Z | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Advisor Total Bond Fund - Class Z | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Advisor Total Bond Fund - Class Z | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Advisor Total Bond Fund - Class Z | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class Z | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Total Bond Fund - Class Z | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class Z | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class Z | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Total Bond Fund - Class Z | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class Z | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Advisor Total Bond Fund - Class Z | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Advisor Total Bond Fund - Class Z | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class Z | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Advisor Total Bond Fund - Class Z | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Advisor Total Bond Fund - Class Z | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class Z | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class Z | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class Z | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class Z | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Total Bond Fund - Class Z | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class Z | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Advisor Total Bond Fund - Class Z | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Advisor Total Bond Fund - Class Z | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class Z | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class Z | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class Z | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Total Bond Fund - Class Z | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class Z | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class Z | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Advisor Total Bond Fund - Class Z | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class Z | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Total Bond Fund - Class Z | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Advisor Total Bond Fund - Class Z | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Advisor Total Bond Fund - Class Z | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Advisor Total Bond Fund - Class Z | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Advisor Total Bond Fund - Class Z | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class Z | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Advisor Total Bond Fund - Class Z | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Total Bond Fund - Class Z | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class Z | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class Z | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class Z | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class M | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Advisor Total Bond Fund - Class M | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Advisor Total Bond Fund - Class M | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Advisor Total Bond Fund - Class M | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Advisor Total Bond Fund - Class M | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class M | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Total Bond Fund - Class M | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class M | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class M | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Total Bond Fund - Class M | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class M | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Advisor Total Bond Fund - Class M | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Advisor Total Bond Fund - Class M | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class M | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Advisor Total Bond Fund - Class M | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Advisor Total Bond Fund - Class M | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class M | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class M | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class M | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class M | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Total Bond Fund - Class M | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class M | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Advisor Total Bond Fund - Class M | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Advisor Total Bond Fund - Class M | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class M | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class M | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class M | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Total Bond Fund - Class M | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class M | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class M | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Advisor Total Bond Fund - Class M | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class M | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Total Bond Fund - Class M | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Advisor Total Bond Fund - Class M | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Advisor Total Bond Fund - Class M | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Advisor Total Bond Fund - Class M | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Advisor Total Bond Fund - Class M | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class M | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Advisor Total Bond Fund - Class M | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Total Bond Fund - Class M | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class M | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class M | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class M | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class I | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Advisor Total Bond Fund - Class I | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Advisor Total Bond Fund - Class I | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Advisor Total Bond Fund - Class I | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Advisor Total Bond Fund - Class I | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class I | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Total Bond Fund - Class I | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class I | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class I | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Total Bond Fund - Class I | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class I | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Advisor Total Bond Fund - Class I | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Advisor Total Bond Fund - Class I | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class I | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Advisor Total Bond Fund - Class I | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Advisor Total Bond Fund - Class I | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class I | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class I | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class I | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class I | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Total Bond Fund - Class I | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class I | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Advisor Total Bond Fund - Class I | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Advisor Total Bond Fund - Class I | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class I | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class I | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class I | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Total Bond Fund - Class I | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class I | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class I | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Advisor Total Bond Fund - Class I | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class I | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Total Bond Fund - Class I | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Advisor Total Bond Fund - Class I | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Advisor Total Bond Fund - Class I | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Advisor Total Bond Fund - Class I | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Advisor Total Bond Fund - Class I | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class I | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Advisor Total Bond Fund - Class I | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Total Bond Fund - Class I | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class I | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class I | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class I | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class C | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Advisor Total Bond Fund - Class C | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Advisor Total Bond Fund - Class C | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Advisor Total Bond Fund - Class C | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Advisor Total Bond Fund - Class C | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class C | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Total Bond Fund - Class C | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class C | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class C | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Total Bond Fund - Class C | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class C | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Advisor Total Bond Fund - Class C | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Advisor Total Bond Fund - Class C | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class C | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Advisor Total Bond Fund - Class C | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Advisor Total Bond Fund - Class C | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class C | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class C | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class C | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class C | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Total Bond Fund - Class C | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class C | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Advisor Total Bond Fund - Class C | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Advisor Total Bond Fund - Class C | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class C | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class C | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class C | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Total Bond Fund - Class C | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class C | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class C | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Advisor Total Bond Fund - Class C | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class C | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Total Bond Fund - Class C | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Advisor Total Bond Fund - Class C | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Advisor Total Bond Fund - Class C | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Advisor Total Bond Fund - Class C | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Advisor Total Bond Fund - Class C | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class C | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Advisor Total Bond Fund - Class C | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Total Bond Fund - Class C | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class C | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class C | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class C | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class A | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.50%
Fidelity Advisor Total Bond Fund - Class A | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Advisor Total Bond Fund - Class A | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Advisor Total Bond Fund - Class A | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Advisor Total Bond Fund - Class A | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class A | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Total Bond Fund - Class A | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class A | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class A | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Total Bond Fund - Class A | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class A | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 54.40%
Fidelity Advisor Total Bond Fund - Class A | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.10%
Fidelity Advisor Total Bond Fund - Class A | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Total Bond Fund - Class A | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.70%
Fidelity Advisor Total Bond Fund - Class A | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 13.70%
Fidelity Advisor Total Bond Fund - Class A | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Advisor Total Bond Fund - Class A | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class A | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class A | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class A | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Total Bond Fund - Class A | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class A | United States  
Holdings [Line Items]  
Percent of Net Asset Value 85.90%
Fidelity Advisor Total Bond Fund - Class A | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.00%
Fidelity Advisor Total Bond Fund - Class A | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Total Bond Fund - Class A | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Total Bond Fund - Class A | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class A | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Total Bond Fund - Class A | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Advisor Total Bond Fund - Class A | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class A | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Advisor Total Bond Fund - Class A | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Total Bond Fund - Class A | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Total Bond Fund - Class A | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.50%
Fidelity Advisor Total Bond Fund - Class A | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Advisor Total Bond Fund - Class A | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.90%
Fidelity Advisor Total Bond Fund - Class A | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.40%
Fidelity Advisor Total Bond Fund - Class A | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Advisor Total Bond Fund - Class A | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Advisor Total Bond Fund - Class A | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Total Bond Fund - Class A | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Total Bond Fund - Class A | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class A | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Total Bond Fund - Class A | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Series Government Bond Index Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 76.40%
Fidelity Series Government Bond Index Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.40%
Fidelity Series Government Bond Index Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Series Government Bond Index Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Series Government Bond Index Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Series Government Bond Index Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Series Government Bond Index Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Series Government Bond Index Fund | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.20%
Fidelity Series Government Bond Index Fund | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 15.90%
Fidelity Series Government Bond Index Fund | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.00%
Fidelity Series Government Bond Index Fund | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 26.50%
Fidelity Series Government Bond Index Fund | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.60%
Fidelity Series Government Bond Index Fund | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Series Government Bond Index Fund | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Series Government Bond Index Fund | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Series Government Bond Index Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 97.80%
Fidelity Series Government Bond Index Fund | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Series Government Bond Index Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Intermediate Government Income Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 76.60%
Fidelity Intermediate Government Income Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.60%
Fidelity Intermediate Government Income Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Intermediate Government Income Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Intermediate Government Income Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Intermediate Government Income Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Intermediate Government Income Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Intermediate Government Income Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Intermediate Government Income Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Intermediate Government Income Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Intermediate Government Income Fund | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Intermediate Government Income Fund | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 14.30%
Fidelity Intermediate Government Income Fund | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 13.40%
Fidelity Intermediate Government Income Fund | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 19.40%
Fidelity Intermediate Government Income Fund | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 41.10%
Fidelity Intermediate Government Income Fund | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.40%
Fidelity Intermediate Government Income Fund | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Intermediate Government Income Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 77.50%
Fidelity Intermediate Government Income Fund | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Fidelity Intermediate Government Income Fund | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Fidelity Intermediate Government Income Fund | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Intermediate Government Income Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Fidelity Government Income Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Government Income Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Government Income Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Government Income Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Government Income Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Government Income Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Government Income Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Government Income Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Government Income Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Government Income Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Government Income Fund | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Government Income Fund | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Government Income Fund | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Government Income Fund | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Government Income Fund | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Government Income Fund | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Government Income Fund | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Government Income Fund | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Government Income Fund | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Government Income Fund | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Government Income Fund | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Government Income Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Government Income Fund | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Government Income Fund | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Government Income Fund | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Government Income Fund | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Government Income Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class Z | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Government Income Fund - Class Z | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Advisor Government Income Fund - Class Z | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Advisor Government Income Fund - Class Z | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Advisor Government Income Fund - Class Z | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Advisor Government Income Fund - Class Z | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class Z | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Government Income Fund - Class Z | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Government Income Fund - Class Z | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Government Income Fund - Class Z | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Government Income Fund - Class Z | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class Z | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Government Income Fund - Class Z | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Advisor Government Income Fund - Class Z | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Advisor Government Income Fund - Class Z | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Advisor Government Income Fund - Class Z | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Government Income Fund - Class Z | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Advisor Government Income Fund - Class Z | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class Z | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class Z | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class Z | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class Z | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Advisor Government Income Fund - Class Z | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Advisor Government Income Fund - Class Z | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Advisor Government Income Fund - Class Z | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Government Income Fund - Class Z | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Advisor Government Income Fund - Class Z | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class M | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Government Income Fund - Class M | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Advisor Government Income Fund - Class M | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Advisor Government Income Fund - Class M | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Advisor Government Income Fund - Class M | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Advisor Government Income Fund - Class M | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class M | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Government Income Fund - Class M | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Government Income Fund - Class M | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Government Income Fund - Class M | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Government Income Fund - Class M | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class M | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Government Income Fund - Class M | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Advisor Government Income Fund - Class M | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Advisor Government Income Fund - Class M | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Advisor Government Income Fund - Class M | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Government Income Fund - Class M | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Advisor Government Income Fund - Class M | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class M | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class M | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class M | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class M | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Advisor Government Income Fund - Class M | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Advisor Government Income Fund - Class M | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Advisor Government Income Fund - Class M | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Government Income Fund - Class M | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Advisor Government Income Fund - Class M | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class I | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Government Income Fund - Class I | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Advisor Government Income Fund - Class I | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Advisor Government Income Fund - Class I | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Advisor Government Income Fund - Class I | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Advisor Government Income Fund - Class I | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class I | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Government Income Fund - Class I | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Government Income Fund - Class I | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Government Income Fund - Class I | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Government Income Fund - Class I | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class I | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Government Income Fund - Class I | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Advisor Government Income Fund - Class I | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Advisor Government Income Fund - Class I | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Advisor Government Income Fund - Class I | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Government Income Fund - Class I | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Advisor Government Income Fund - Class I | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class I | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class I | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class I | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class I | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Advisor Government Income Fund - Class I | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Advisor Government Income Fund - Class I | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Advisor Government Income Fund - Class I | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Government Income Fund - Class I | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Advisor Government Income Fund - Class I | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class C | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Government Income Fund - Class C | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Advisor Government Income Fund - Class C | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Advisor Government Income Fund - Class C | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Advisor Government Income Fund - Class C | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Advisor Government Income Fund - Class C | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class C | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Government Income Fund - Class C | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Government Income Fund - Class C | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Government Income Fund - Class C | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Government Income Fund - Class C | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class C | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Government Income Fund - Class C | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Advisor Government Income Fund - Class C | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Advisor Government Income Fund - Class C | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Advisor Government Income Fund - Class C | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Government Income Fund - Class C | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Advisor Government Income Fund - Class C | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class C | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class C | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class C | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class C | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Advisor Government Income Fund - Class C | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Advisor Government Income Fund - Class C | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Advisor Government Income Fund - Class C | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Government Income Fund - Class C | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Advisor Government Income Fund - Class C | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class A | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.30%
Fidelity Advisor Government Income Fund - Class A | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.80%
Fidelity Advisor Government Income Fund - Class A | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 16.50%
Fidelity Advisor Government Income Fund - Class A | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.00%
Fidelity Advisor Government Income Fund - Class A | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.90%
Fidelity Advisor Government Income Fund - Class A | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Advisor Government Income Fund - Class A | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Government Income Fund - Class A | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Government Income Fund - Class A | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Government Income Fund - Class A | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Government Income Fund - Class A | CD0Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class A | CD1Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.10%
Fidelity Advisor Government Income Fund - Class A | CD2Member  
Holdings [Line Items]  
Percent of Net Asset Value 27.50%
Fidelity Advisor Government Income Fund - Class A | CD3Member  
Holdings [Line Items]  
Percent of Net Asset Value 28.70%
Fidelity Advisor Government Income Fund - Class A | CD4Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.10%
Fidelity Advisor Government Income Fund - Class A | CD5Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Government Income Fund - Class A | CD6Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.00%
Fidelity Advisor Government Income Fund - Class A | CD7Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class A | CD8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class A | CD9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class A | CD10Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Advisor Government Income Fund - Class A | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 50.80%
Fidelity Advisor Government Income Fund - Class A | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Advisor Government Income Fund - Class A | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.80%
Fidelity Advisor Government Income Fund - Class A | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Advisor Government Income Fund - Class A | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Advisor Government Income Fund - Class A | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Environmental Bond Fund | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Environmental Bond Fund | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Environmental Bond Fund | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Environmental Bond Fund | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Environmental Bond Fund | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Environmental Bond Fund | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Environmental Bond Fund | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Environmental Bond Fund | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Environmental Bond Fund | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Environmental Bond Fund | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Environmental Bond Fund | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Environmental Bond Fund | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Environmental Bond Fund | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Environmental Bond Fund | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Environmental Bond Fund | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Environmental Bond Fund | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Environmental Bond Fund | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Environmental Bond Fund | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Environmental Bond Fund | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Environmental Bond Fund | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Environmental Bond Fund | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Environmental Bond Fund | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Environmental Bond Fund | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Environmental Bond Fund | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Environmental Bond Fund | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Environmental Bond Fund | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Environmental Bond Fund | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Environmental Bond Fund | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Environmental Bond Fund | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Environmental Bond Fund | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Environmental Bond Fund | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Environmental Bond Fund | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Environmental Bond Fund | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Environmental Bond Fund | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Environmental Bond Fund | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Environmental Bond Fund | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Environmental Bond Fund | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class Z | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Advisor Environmental Bond Fund - Class Z | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Advisor Environmental Bond Fund - Class Z | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Advisor Environmental Bond Fund - Class Z | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Environmental Bond Fund - Class Z | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Environmental Bond Fund - Class Z | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class Z | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Environmental Bond Fund - Class Z | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class Z | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class Z | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class Z | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Advisor Environmental Bond Fund - Class Z | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class Z | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Advisor Environmental Bond Fund - Class Z | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Advisor Environmental Bond Fund - Class Z | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Advisor Environmental Bond Fund - Class Z | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Advisor Environmental Bond Fund - Class Z | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class Z | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class Z | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Advisor Environmental Bond Fund - Class Z | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Advisor Environmental Bond Fund - Class Z | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Environmental Bond Fund - Class Z | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class Z | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class Z | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Advisor Environmental Bond Fund - Class Z | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class Z | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Advisor Environmental Bond Fund - Class Z | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class Z | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class Z | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Advisor Environmental Bond Fund - Class Z | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Advisor Environmental Bond Fund - Class Z | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Advisor Environmental Bond Fund - Class Z | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class Z | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Advisor Environmental Bond Fund - Class Z | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Environmental Bond Fund - Class Z | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Advisor Environmental Bond Fund - Class Z | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Environmental Bond Fund - Class Z | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class M | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Advisor Environmental Bond Fund - Class M | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Advisor Environmental Bond Fund - Class M | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Advisor Environmental Bond Fund - Class M | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Environmental Bond Fund - Class M | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Environmental Bond Fund - Class M | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class M | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Environmental Bond Fund - Class M | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class M | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class M | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class M | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Advisor Environmental Bond Fund - Class M | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class M | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Advisor Environmental Bond Fund - Class M | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Advisor Environmental Bond Fund - Class M | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Advisor Environmental Bond Fund - Class M | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Advisor Environmental Bond Fund - Class M | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class M | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class M | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Advisor Environmental Bond Fund - Class M | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Advisor Environmental Bond Fund - Class M | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Environmental Bond Fund - Class M | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class M | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class M | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Advisor Environmental Bond Fund - Class M | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class M | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Advisor Environmental Bond Fund - Class M | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class M | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class M | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Advisor Environmental Bond Fund - Class M | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Advisor Environmental Bond Fund - Class M | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Advisor Environmental Bond Fund - Class M | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class M | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Advisor Environmental Bond Fund - Class M | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Environmental Bond Fund - Class M | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Advisor Environmental Bond Fund - Class M | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Environmental Bond Fund - Class M | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class I | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Advisor Environmental Bond Fund - Class I | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Advisor Environmental Bond Fund - Class I | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Advisor Environmental Bond Fund - Class I | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Environmental Bond Fund - Class I | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Environmental Bond Fund - Class I | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class I | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Environmental Bond Fund - Class I | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class I | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class I | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class I | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Advisor Environmental Bond Fund - Class I | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class I | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Advisor Environmental Bond Fund - Class I | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Advisor Environmental Bond Fund - Class I | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Advisor Environmental Bond Fund - Class I | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Advisor Environmental Bond Fund - Class I | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class I | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class I | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Advisor Environmental Bond Fund - Class I | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Advisor Environmental Bond Fund - Class I | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Environmental Bond Fund - Class I | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class I | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class I | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Advisor Environmental Bond Fund - Class I | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class I | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Advisor Environmental Bond Fund - Class I | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class I | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class I | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Advisor Environmental Bond Fund - Class I | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Advisor Environmental Bond Fund - Class I | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Advisor Environmental Bond Fund - Class I | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class I | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Advisor Environmental Bond Fund - Class I | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Environmental Bond Fund - Class I | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Advisor Environmental Bond Fund - Class I | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Environmental Bond Fund - Class I | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class C | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Advisor Environmental Bond Fund - Class C | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Advisor Environmental Bond Fund - Class C | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Advisor Environmental Bond Fund - Class C | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Environmental Bond Fund - Class C | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Environmental Bond Fund - Class C | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class C | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Environmental Bond Fund - Class C | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class C | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class C | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class C | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Advisor Environmental Bond Fund - Class C | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class C | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Advisor Environmental Bond Fund - Class C | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Advisor Environmental Bond Fund - Class C | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Advisor Environmental Bond Fund - Class C | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Advisor Environmental Bond Fund - Class C | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class C | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class C | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Advisor Environmental Bond Fund - Class C | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Advisor Environmental Bond Fund - Class C | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Environmental Bond Fund - Class C | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class C | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class C | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Advisor Environmental Bond Fund - Class C | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class C | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Advisor Environmental Bond Fund - Class C | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class C | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class C | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Advisor Environmental Bond Fund - Class C | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Advisor Environmental Bond Fund - Class C | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Advisor Environmental Bond Fund - Class C | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class C | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Advisor Environmental Bond Fund - Class C | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Environmental Bond Fund - Class C | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Advisor Environmental Bond Fund - Class C | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Environmental Bond Fund - Class C | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class A | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 30.40%
Fidelity Advisor Environmental Bond Fund - Class A | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.10%
Fidelity Advisor Environmental Bond Fund - Class A | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 6.20%
Fidelity Advisor Environmental Bond Fund - Class A | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Advisor Environmental Bond Fund - Class A | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Advisor Environmental Bond Fund - Class A | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class A | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Advisor Environmental Bond Fund - Class A | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class A | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class A | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Advisor Environmental Bond Fund - Class A | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 56.60%
Fidelity Advisor Environmental Bond Fund - Class A | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class A | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Advisor Environmental Bond Fund - Class A | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 11.50%
Fidelity Advisor Environmental Bond Fund - Class A | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.00%
Fidelity Advisor Environmental Bond Fund - Class A | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Advisor Environmental Bond Fund - Class A | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class A | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Advisor Environmental Bond Fund - Class A | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.00%
Fidelity Advisor Environmental Bond Fund - Class A | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Advisor Environmental Bond Fund - Class A | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Advisor Environmental Bond Fund - Class A | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Advisor Environmental Bond Fund - Class A | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class A | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Advisor Environmental Bond Fund - Class A | Italy  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Advisor Environmental Bond Fund - Class A | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Advisor Environmental Bond Fund - Class A | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Advisor Environmental Bond Fund - Class A | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class A | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 43.50%
Fidelity Advisor Environmental Bond Fund - Class A | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 35.50%
Fidelity Advisor Environmental Bond Fund - Class A | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.70%
Fidelity Advisor Environmental Bond Fund - Class A | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Advisor Environmental Bond Fund - Class A | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Advisor Environmental Bond Fund - Class A | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Advisor Environmental Bond Fund - Class A | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Advisor Environmental Bond Fund - Class A | AAUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Advisor Environmental Bond Fund - Class A | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%