v3.25.3
Shareholder Report, Holdings (Details)
Aug. 31, 2025
Fidelity Total Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 22.30%
Fidelity Total Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.30%
Fidelity Total Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.10%
Fidelity Total Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.40%
Fidelity Total Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Fidelity Total Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Total Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Total Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Total Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Total Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Total Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 53.70%
Fidelity Total Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.50%
Fidelity Total Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Total Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.20%
Fidelity Total Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.70%
Fidelity Total Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Total Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.80%
Fidelity Total Bond ETF | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Fidelity Total Bond ETF | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.10%
Fidelity Total Bond ETF | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 88.00%
Fidelity Total Bond ETF | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity Total Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Total Bond ETF | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Total Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Total Bond ETF | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Total Bond ETF | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Total Bond ETF | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Total Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Total Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Total Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 33.60%
Fidelity Total Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 27.20%
Fidelity Total Bond ETF | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 20.10%
Fidelity Total Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Fidelity Total Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.00%
Fidelity Total Bond ETF | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.20%
Fidelity Total Bond ETF | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Total Bond ETF | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Total Bond ETF | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Total Bond ETF | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond ETF | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Total Bond ETF | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Tactical Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 31.70%
Fidelity Tactical Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.40%
Fidelity Tactical Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Tactical Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Tactical Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Tactical Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Tactical Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Tactical Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Tactical Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Tactical Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Tactical Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 44.10%
Fidelity Tactical Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Tactical Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Tactical Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Tactical Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.30%
Fidelity Tactical Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 19.70%
Fidelity Tactical Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 9.00%
Fidelity Tactical Bond ETF | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity Tactical Bond ETF | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Tactical Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity Tactical Bond ETF | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Tactical Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Tactical Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 77.70%
Fidelity Tactical Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Fidelity Tactical Bond ETF | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Tactical Bond ETF | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Tactical Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Tactical Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 6.50%
Fidelity Tactical Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 3.20%
Fidelity Tactical Bond ETF | Luxembourg  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Tactical Bond ETF | Brazil  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Tactical Bond ETF | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Tactical Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 44.10%
Fidelity Tactical Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 40.20%
Fidelity Tactical Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Tactical Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Tactical Bond ETF | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Tactical Bond ETF | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.30%
Fidelity Tactical Bond ETF | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity Tactical Bond ETF | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Tactical Bond ETF | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Tactical Bond ETF | AAMunicipalSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Tactical Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Sustainable Low Duration Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 23.00%
Fidelity Sustainable Low Duration Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.00%
Fidelity Sustainable Low Duration Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Sustainable Low Duration Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Sustainable Low Duration Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Sustainable Low Duration Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Sustainable Low Duration Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Sustainable Low Duration Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Sustainable Low Duration Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Sustainable Low Duration Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Sustainable Low Duration Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 33.00%
Fidelity Sustainable Low Duration Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.20%
Fidelity Sustainable Low Duration Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Sustainable Low Duration Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 26.00%
Fidelity Sustainable Low Duration Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.70%
Fidelity Sustainable Low Duration Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Sustainable Low Duration Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Sustainable Low Duration Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity Sustainable Low Duration Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 91.50%
Fidelity Sustainable Low Duration Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Sustainable Low Duration Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Sustainable Low Duration Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 6.30%
Fidelity Sustainable Low Duration Bond ETF | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Sustainable Low Duration Bond ETF | Chile  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Sustainable Low Duration Bond ETF | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Sustainable Low Duration Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 33.00%
Fidelity Sustainable Low Duration Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 49.30%
Fidelity Sustainable Low Duration Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Fidelity Sustainable Low Duration Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Sustainable Low Duration Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity Sustainable Core Plus Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 20.60%
Fidelity Sustainable Core Plus Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 10.50%
Fidelity Sustainable Core Plus Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Fidelity Sustainable Core Plus Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.00%
Fidelity Sustainable Core Plus Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity Sustainable Core Plus Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.60%
Fidelity Sustainable Core Plus Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Sustainable Core Plus Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Sustainable Core Plus Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Sustainable Core Plus Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Sustainable Core Plus Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 49.50%
Fidelity Sustainable Core Plus Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Fidelity Sustainable Core Plus Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Sustainable Core Plus Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 10.80%
Fidelity Sustainable Core Plus Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 17.40%
Fidelity Sustainable Core Plus Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.60%
Fidelity Sustainable Core Plus Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Fidelity Sustainable Core Plus Bond ETF | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity Sustainable Core Plus Bond ETF | QDDMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Sustainable Core Plus Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Sustainable Core Plus Bond ETF | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Sustainable Core Plus Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Sustainable Core Plus Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 87.20%
Fidelity Sustainable Core Plus Bond ETF | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Sustainable Core Plus Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Sustainable Core Plus Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Sustainable Core Plus Bond ETF | France  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Sustainable Core Plus Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Sustainable Core Plus Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Sustainable Core Plus Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Sustainable Core Plus Bond ETF | MultinationalMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Sustainable Core Plus Bond ETF | Spain  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Sustainable Core Plus Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 31.10%
Fidelity Sustainable Core Plus Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 40.00%
Fidelity Sustainable Core Plus Bond ETF | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 18.40%
Fidelity Sustainable Core Plus Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.50%
Fidelity Sustainable Core Plus Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Sustainable Core Plus Bond ETF | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Sustainable Core Plus Bond ETF | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.60%
Fidelity Sustainable Core Plus Bond ETF | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Sustainable Core Plus Bond ETF | AAPreferredStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Sustainable Core Plus Bond ETF | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Sustainable Core Plus Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Low Duration Bond Factor ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 12.20%
Fidelity Low Duration Bond Factor ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity Low Duration Bond Factor ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Low Duration Bond Factor ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.10%
Fidelity Low Duration Bond Factor ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Low Duration Bond Factor ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity Low Duration Bond Factor ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Low Duration Bond Factor ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Low Duration Bond Factor ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.30%
Fidelity Low Duration Bond Factor ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Low Duration Bond Factor ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.20%
Fidelity Low Duration Bond Factor ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 26.60%
Fidelity Low Duration Bond Factor ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 51.60%
Fidelity Low Duration Bond Factor ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.00%
Fidelity Low Duration Bond Factor ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Low Duration Bond Factor ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Low Duration Bond Factor ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Low Duration Bond Factor ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 58.30%
Fidelity Low Duration Bond Factor ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Low Duration Bond Factor ETF | France  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity Low Duration Bond Factor ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity Low Duration Bond Factor ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Low Duration Bond Factor ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 8.20%
Fidelity Low Duration Bond Factor ETF | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Low Duration Bond Factor ETF | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity Low Duration Bond Factor ETF | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 11.90%
Fidelity Low Duration Bond Factor ETF | Sweden  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Low Duration Bond Factor ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 12.20%
Fidelity Low Duration Bond Factor ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 86.80%
Fidelity Low Duration Bond Factor ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Limited Term Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Fidelity Limited Term Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Limited Term Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Limited Term Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Fidelity Limited Term Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Fidelity Limited Term Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Limited Term Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Limited Term Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Limited Term Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Limited Term Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Limited Term Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Fidelity Limited Term Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 7.30%
Fidelity Limited Term Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Limited Term Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 24.60%
Fidelity Limited Term Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 38.80%
Fidelity Limited Term Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Limited Term Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.40%
Fidelity Limited Term Bond ETF | QDCCCCCCMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Limited Term Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity Limited Term Bond ETF | QDEquitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Limited Term Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Limited Term Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 77.00%
Fidelity Limited Term Bond ETF | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity Limited Term Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Limited Term Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Limited Term Bond ETF | France  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Limited Term Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Limited Term Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity Limited Term Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Limited Term Bond ETF | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Limited Term Bond ETF | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Limited Term Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.00%
Fidelity Limited Term Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 70.20%
Fidelity Limited Term Bond ETF | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Limited Term Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 9.30%
Fidelity Limited Term Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity Limited Term Bond ETF | AABankLoanObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Limited Term Bond ETF | AAForeignGovernmentandGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.20%
Fidelity Limited Term Bond ETF | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Limited Term Bond ETF | AACommonStocksMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Limited Term Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Investment Grade Securitized ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 32.40%
Fidelity Investment Grade Securitized ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 25.10%
Fidelity Investment Grade Securitized ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 21.70%
Fidelity Investment Grade Securitized ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.70%
Fidelity Investment Grade Securitized ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 5.10%
Fidelity Investment Grade Securitized ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Fidelity Investment Grade Securitized ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.50%
Fidelity Investment Grade Securitized ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.80%
Fidelity Investment Grade Securitized ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Investment Grade Securitized ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Investment Grade Securitized ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 91.00%
Fidelity Investment Grade Securitized ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.30%
Fidelity Investment Grade Securitized ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Investment Grade Securitized ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Investment Grade Securitized ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 16.60%
Fidelity Investment Grade Securitized ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 100.00%
Fidelity Investment Grade Securitized ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 0.00%
Fidelity Investment Grade Securitized ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.20%
Fidelity Investment Grade Securitized ETF | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 88.80%
Fidelity Investment Grade Securitized ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 9.90%
Fidelity Investment Grade Securitized ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 21.30%
Fidelity Investment Grade Securitized ETF | AAOptionsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Investment Grade Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 34.20%
Fidelity Investment Grade Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 11.80%
Fidelity Investment Grade Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 4.10%
Fidelity Investment Grade Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 3.90%
Fidelity Investment Grade Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Investment Grade Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.80%
Fidelity Investment Grade Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Investment Grade Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Investment Grade Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Investment Grade Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Investment Grade Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 60.70%
Fidelity Investment Grade Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.90%
Fidelity Investment Grade Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Investment Grade Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Fidelity Investment Grade Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 16.90%
Fidelity Investment Grade Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.10%
Fidelity Investment Grade Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Investment Grade Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.80%
Fidelity Investment Grade Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Investment Grade Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 90.00%
Fidelity Investment Grade Bond ETF | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.80%
Fidelity Investment Grade Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Investment Grade Bond ETF | Mexico  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Investment Grade Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Investment Grade Bond ETF | BailiwickOfJerseyMember  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Investment Grade Bond ETF | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Investment Grade Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Investment Grade Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Investment Grade Bond ETF | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 0.30%
Fidelity Investment Grade Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 46.00%
Fidelity Investment Grade Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 25.00%
Fidelity Investment Grade Bond ETF | AAUSGovernmentAgencyMortgageSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.70%
Fidelity Investment Grade Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 9.00%
Fidelity Investment Grade Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Fidelity Investment Grade Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.90%
Fidelity Corporate Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.80%
Fidelity Corporate Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity Corporate Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.40%
Fidelity Corporate Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 2.00%
Fidelity Corporate Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Corporate Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.90%
Fidelity Corporate Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Corporate Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.40%
Fidelity Corporate Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Corporate Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Corporate Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Fidelity Corporate Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Corporate Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.00%
Fidelity Corporate Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 60.70%
Fidelity Corporate Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 5.50%
Fidelity Corporate Bond ETF | QDBMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.70%
Fidelity Corporate Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Corporate Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.40%
Fidelity Corporate Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 81.30%
Fidelity Corporate Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 4.40%
Fidelity Corporate Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 2.60%
Fidelity Corporate Bond ETF | France  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Corporate Bond ETF | Switzerland  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Corporate Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Fidelity Corporate Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.00%
Fidelity Corporate Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity Corporate Bond ETF | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Corporate Bond ETF | Spain  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Corporate Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 8.50%
Fidelity Corporate Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 88.00%
Fidelity Corporate Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.50%
Fidelity Corporate Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Corporate Bond ETF | AAPreferredSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.40%
Fidelity Corporate Bond ETF | AAOtherInvestmentsMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Corporate Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.40%
Fidelity Low Duration Bond ETF | TH0Member  
Holdings [Line Items]  
Percent of Net Asset Value 18.40%
Fidelity Low Duration Bond ETF | TH1Member  
Holdings [Line Items]  
Percent of Net Asset Value 7.20%
Fidelity Low Duration Bond ETF | TH2Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.60%
Fidelity Low Duration Bond ETF | TH3Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Low Duration Bond ETF | TH4Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.30%
Fidelity Low Duration Bond ETF | TH5Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.20%
Fidelity Low Duration Bond ETF | TH6Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Low Duration Bond ETF | TH7Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Low Duration Bond ETF | TH8Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Low Duration Bond ETF | TH9Member  
Holdings [Line Items]  
Percent of Net Asset Value 1.10%
Fidelity Low Duration Bond ETF | QDUSGovernmentandUSGovernmentAgencyObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 25.60%
Fidelity Low Duration Bond ETF | QDAAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.70%
Fidelity Low Duration Bond ETF | QDAAMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.70%
Fidelity Low Duration Bond ETF | QDAMember  
Holdings [Line Items]  
Percent of Net Asset Value 26.20%
Fidelity Low Duration Bond ETF | QDBBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 14.70%
Fidelity Low Duration Bond ETF | QDBBMember  
Holdings [Line Items]  
Percent of Net Asset Value 0.10%
Fidelity Low Duration Bond ETF | QDNotRatedMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.70%
Fidelity Low Duration Bond ETF | QDShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%
Fidelity Low Duration Bond ETF | United States  
Holdings [Line Items]  
Percent of Net Asset Value 76.90%
Fidelity Low Duration Bond ETF | GrandCaymanUKOverseasTerMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.40%
Fidelity Low Duration Bond ETF | United Kingdom  
Holdings [Line Items]  
Percent of Net Asset Value 4.20%
Fidelity Low Duration Bond ETF | Ireland  
Holdings [Line Items]  
Percent of Net Asset Value 1.50%
Fidelity Low Duration Bond ETF | Germany  
Holdings [Line Items]  
Percent of Net Asset Value 2.40%
Fidelity Low Duration Bond ETF | OtherMember  
Holdings [Line Items]  
Percent of Net Asset Value 4.60%
Fidelity Low Duration Bond ETF | Canada  
Holdings [Line Items]  
Percent of Net Asset Value 3.50%
Fidelity Low Duration Bond ETF | Japan  
Holdings [Line Items]  
Percent of Net Asset Value 1.00%
Fidelity Low Duration Bond ETF | Netherlands  
Holdings [Line Items]  
Percent of Net Asset Value 1.70%
Fidelity Low Duration Bond ETF | Australia  
Holdings [Line Items]  
Percent of Net Asset Value 0.80%
Fidelity Low Duration Bond ETF | AAUSTreasuryObligationsMember  
Holdings [Line Items]  
Percent of Net Asset Value 25.60%
Fidelity Low Duration Bond ETF | AACorporateBondsMember  
Holdings [Line Items]  
Percent of Net Asset Value 45.80%
Fidelity Low Duration Bond ETF | AAAssetBackedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 22.40%
Fidelity Low Duration Bond ETF | AACMOsandOtherMortgageRelatedSecuritiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 2.90%
Fidelity Low Duration Bond ETF | AAShortTermInvestmentsandNetOtherAssetsLiabilitiesMember  
Holdings [Line Items]  
Percent of Net Asset Value 3.30%