<?xml version="1.0" encoding="utf-8"?>
<xbrl
  xmlns="http://www.xbrl.org/2003/instance"
  xmlns:dei="http://xbrl.sec.gov/dei/2024"
  xmlns:fmr="http://www.fidelity.com/20251030"
  xmlns:iso4217="http://www.xbrl.org/2003/iso4217"
  xmlns:link="http://www.xbrl.org/2003/linkbase"
  xmlns:oef="http://xbrl.sec.gov/oef/2024q3"
  xmlns:xbrldi="http://xbrl.org/2006/xbrldi"
  xmlns:xhtml="http://www.w3.org/1999/xhtml"
  xmlns:xlink="http://www.w3.org/1999/xlink">
    <link:schemaRef xlink:href="fmr-20251030.xsd" xlink:type="simple"/>
    <context id="Trust">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088100">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088100Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088099">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088099Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088101">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088101Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000205023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000205023Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2015">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-01-01</startDate>
            <endDate>2015-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088097Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088100Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088100Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088100Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088099Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088099Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088099Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088101Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088101Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088101Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000205023Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000205023Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000205023Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-AMCIZPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_contentCd_SBX-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000211071Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000065215Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2015">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-01-01</startDate>
            <endDate>2015-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000100043Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000017676Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_contentCd_SS1-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000153158Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIX139Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIX139Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIX139Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesShort-TermCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000048583Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_HighPortfolioTurnoverMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:HighPortfolioTurnoverMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_contentCd_LIG-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2015">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-01-01</startDate>
            <endDate>2015-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000069436Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesInvestmentGradeBondFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000023604Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_IncomeRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IncomeRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_USGovernmentObligationsRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USGovernmentObligationsRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskMoneyMarketFundMayNotPreserveDollarMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskMoneyMarketFundMayNotPreserveDollarMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskMoneyMarketFundSponsorMayNotProvideSupportMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskMoneyMarketFundSponsorMayNotProvideSupportMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeriesGovernmentMoneyMarketFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000053607Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000168450Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000177581Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityFlexUSBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000056354Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_contentCd_CBD-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2015">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-01-01</startDate>
            <endDate>2015-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000088096Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB004Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <context id="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityCorporateBondFund-RetailPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000028761Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2015-10-30</startDate>
            <endDate>2025-10-30</endDate>
        </period>
    </context>
    <unit id="usd">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <unit id="holding">
        <measure>shares</measure>
    </unit>
    <dei:DocumentType contextRef="Trust" id="ixv-55604">485BPOS</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="Trust" id="ixv-55605">2025-10-30</dei:DocumentPeriodEndDate>
    <dei:AmendmentFlag contextRef="Trust" id="ixv-55606">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey contextRef="Trust" id="ixv-55607">0000035315</dei:EntityCentralIndexKey>
    <dei:EntityInvCompanyType contextRef="Trust" id="ixv-55608">N-1A</dei:EntityInvCompanyType>
    <dei:EntityRegistrantName contextRef="Trust" id="ixv-55609">Fidelity Salem Street Trust</dei:EntityRegistrantName>
    <oef:RiskReturnHeading contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-248">


     Fund Summary

     Fund /Class:
     Fidelity&#xae; Corporate Bond Fund
     /Fidelity Advisor&#xae; Corporate Bond Fund A, M, C, I, Z &#160;

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-263">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-268">


     Fidelity&#xae; Corporate Bond Fund seeks a high level of current income.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-273">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-279">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.


      You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $



       50,000



      in the fund or certain other Fidelity

      &#xae;

      funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 33

      of the prospectus



     and in

     the sales charge

     waiver appendix to

     the prospectus.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ExpenseBreakpointDiscounts contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-285">

      You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $



       50,000



      in the fund or certain other Fidelity

      &#xae;

      funds. More information about these and other discounts is available from your investment professional and in the "Fund Distribution" section beginning on page 33

      of the prospectus

     </oef:ExpenseBreakpointDiscounts>
    <oef:ExpenseBreakpointMinimumInvestmentRequiredAmount
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      decimals="0"
      id="ixv-58285"
      unitRef="usd">50000</oef:ExpenseBreakpointMinimumInvestmentRequiredAmount>
    <oef:ShareholderFeesCaption contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-308">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:MaximumCumulativeSalesChargeOverOfferingPrice
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="4"
      id="ixv-58286"
      unitRef="pure">0.0400</oef:MaximumCumulativeSalesChargeOverOfferingPrice>
    <oef:MaximumCumulativeSalesChargeOverOfferingPrice
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="4"
      id="ixv-58287"
      unitRef="pure">0.0400</oef:MaximumCumulativeSalesChargeOverOfferingPrice>
    <oef:MaximumCumulativeSalesChargeOverOfferingPrice
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="4"
      id="ixv-58288"
      unitRef="pure">0</oef:MaximumCumulativeSalesChargeOverOfferingPrice>
    <oef:MaximumCumulativeSalesChargeOverOfferingPrice
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="4"
      id="ixv-58289"
      unitRef="pure">0</oef:MaximumCumulativeSalesChargeOverOfferingPrice>
    <oef:MaximumCumulativeSalesChargeOverOfferingPrice
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="4"
      id="ixv-58290"
      unitRef="pure">0</oef:MaximumCumulativeSalesChargeOverOfferingPrice>
    <oef:MaximumDeferredSalesChargeOverOther
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="4"
      id="footnoteACBD-PROS000028761SHF_AC000088097"
      unitRef="pure">0</oef:MaximumDeferredSalesChargeOverOther>
    <oef:MaximumDeferredSalesChargeOverOther
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="4"
      id="footnoteACBD-PROS000028761SHF_AC000088100"
      unitRef="pure">0</oef:MaximumDeferredSalesChargeOverOther>
    <oef:MaximumDeferredSalesChargeOverOther
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="4"
      id="footnoteACBD-PROS000028761SHF_BC000088099"
      unitRef="pure">0.0100</oef:MaximumDeferredSalesChargeOverOther>
    <oef:MaximumDeferredSalesChargeOverOther
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="4"
      id="ixv-58294"
      unitRef="pure">0</oef:MaximumDeferredSalesChargeOverOther>
    <oef:MaximumDeferredSalesChargeOverOther
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="4"
      id="ixv-58295"
      unitRef="pure">0</oef:MaximumDeferredSalesChargeOverOther>
    <oef:ExpensesDeferredChargesTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-414">

      Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% and 0.25%, respectively.

     </oef:ExpensesDeferredChargesTextBlock>
    <oef:ExpensesDeferredChargesTextBlock contextRef="Pid_S000028761_Cid_C000088099" id="ixv-424">

      On Class C shares redeemed less than one year after purchase.

     </oef:ExpensesDeferredChargesTextBlock>
    <oef:OperatingExpensesCaption contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-429">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58296"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58297"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58298"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58299"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="ixv-58300"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58301"
      unitRef="pure">0.0025</oef:DistributionAndService12b1FeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58302"
      unitRef="pure">0.0025</oef:DistributionAndService12b1FeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58303"
      unitRef="pure">0.0100</oef:DistributionAndService12b1FeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58304"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="ixv-58305"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58306"
      unitRef="pure">0.0017</oef:OtherExpensesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58307"
      unitRef="pure">0.0020</oef:OtherExpensesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58308"
      unitRef="pure">0.0017</oef:OtherExpensesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58309"
      unitRef="pure">0.0015</oef:OtherExpensesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="ixv-58310"
      unitRef="pure">0.0005</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58311"
      unitRef="pure">0.0077</oef:ExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58312"
      unitRef="pure">0.0080</oef:ExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58313"
      unitRef="pure">0.0152</oef:ExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58314"
      unitRef="pure">0.0050</oef:ExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="ixv-58315"
      unitRef="pure">0.0040</oef:ExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58316"
      unitRef="pure">-0.0000</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58317"
      unitRef="pure">-0.0000</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58318"
      unitRef="pure">-0.0000</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58319"
      unitRef="pure">-0.0000</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="footnoteS000028761ACBD-PROAOE_AC000205023_FW"
      unitRef="pure">-0.0004</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="6"
      id="ixv-58321"
      unitRef="pure">0.0077</oef:NetExpensesOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="6"
      id="ixv-58322"
      unitRef="pure">0.0080</oef:NetExpensesOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="6"
      id="ixv-58323"
      unitRef="pure">0.0152</oef:NetExpensesOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="6"
      id="ixv-58324"
      unitRef="pure">0.0050</oef:NetExpensesOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="6"
      id="ixv-58325"
      unitRef="pure">0.0036</oef:NetExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-663">2026-12-31</oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-672">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated and if you hold your shares:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58326"
      unitRef="usd">475</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58327"
      unitRef="usd">475</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58328"
      unitRef="usd">478</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58329"
      unitRef="usd">478</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58330"
      unitRef="usd">255</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58331"
      unitRef="usd">155</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58332"
      unitRef="usd">51</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58333"
      unitRef="usd">51</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58334"
      unitRef="usd">37</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58335"
      unitRef="usd">37</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58336"
      unitRef="usd">636</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58337"
      unitRef="usd">636</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58338"
      unitRef="usd">645</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58339"
      unitRef="usd">645</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58340"
      unitRef="usd">480</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58341"
      unitRef="usd">480</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58342"
      unitRef="usd">160</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58343"
      unitRef="usd">160</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58344"
      unitRef="usd">123</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58345"
      unitRef="usd">123</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58346"
      unitRef="usd">811</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58347"
      unitRef="usd">811</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58348"
      unitRef="usd">826</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58349"
      unitRef="usd">826</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58350"
      unitRef="usd">829</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58351"
      unitRef="usd">829</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58352"
      unitRef="usd">280</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58353"
      unitRef="usd">280</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58354"
      unitRef="usd">219</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58355"
      unitRef="usd">219</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58356"
      unitRef="usd">1316</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="Pid_S000028761_Cid_C000088097"
      decimals="0"
      id="ixv-58357"
      unitRef="usd">1316</oef:ExpenseExampleNoRedemptionYear10>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58358"
      unitRef="usd">1350</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="Pid_S000028761_Cid_C000088100"
      decimals="0"
      id="ixv-58359"
      unitRef="usd">1350</oef:ExpenseExampleNoRedemptionYear10>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58360"
      unitRef="usd">1610</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="Pid_S000028761_Cid_C000088099"
      decimals="0"
      id="ixv-58361"
      unitRef="usd">1610</oef:ExpenseExampleNoRedemptionYear10>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58362"
      unitRef="usd">628</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="Pid_S000028761_Cid_C000088101"
      decimals="0"
      id="ixv-58363"
      unitRef="usd">628</oef:ExpenseExampleNoRedemptionYear10>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58364"
      unitRef="usd">500</oef:ExpenseExampleYear10>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="Pid_S000028761_Cid_C000205023"
      decimals="0"
      id="ixv-58365"
      unitRef="usd">500</oef:ExpenseExampleNoRedemptionYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-980">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-985">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       43


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      decimals="4"
      id="ixv-58366"
      unitRef="pure">0.43</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-994">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000028761_contentCd_ACBD-PRO" id="ixv-999">




        Normally investing at least 80% of assets in corporate bonds and other corporate debt securities and repurchase agreements for those securities.

     Corporate debt securities are bonds and other debt securities issued by corporations and other business structures to borrow money. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security. Corporate debt securities include repurchase agreements with corporate counterparties and other securities, such as hybrids and synthetic securities, believed to have corporate debt-like characteristics, (e.g., securities classified as Tier 2 Regulatory capital, securities that rank above share capital in an insolvency waterfall, securities with maturity dates and non-cancellable interest payment structures).
     A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price.
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Normally investing primarily in investment-grade corporate debt securities and repurchase agreements for those securities.
      Managing the fund to have similar overall interest rate risk to the Bloomberg U.S. Credit Bond Index.
      Investing in domestic and foreign issuers.
      Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
      Investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
      Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity&#xae; funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-1033">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_ForeignExposureMember"
      id="ixv-1042">



      Foreign Exposure.

     Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_PrepaymentMember"
      id="ixv-1051">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-1060">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.
     Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_LeverageRiskMember"
      id="ixv-1077">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-1087">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-1095">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1104">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1109">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.



     The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear

     in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     Visit



      institutional.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1115">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1124">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1130">

      institutional.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1135">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:BarChartNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1139">




      The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.




   </oef:BarChartNarrativeTextBlock>
    <oef:BarChartDoesNotReflectSalesLoads
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1142">

      The returns in the bar chart do not reflect any applicable sales charges; if sales charges were reflected, returns would be lower than those shown.

     </oef:BarChartDoesNotReflectSalesLoads>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2015"
      decimals="INF"
      id="ixv-58367"
      unitRef="pure">-0.0176</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2016"
      decimals="INF"
      id="ixv-58368"
      unitRef="pure">0.0613</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2017"
      decimals="INF"
      id="ixv-58369"
      unitRef="pure">0.0646</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2018"
      decimals="INF"
      id="ixv-58370"
      unitRef="pure">-0.0291</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2019"
      decimals="INF"
      id="ixv-58371"
      unitRef="pure">0.1409</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2020"
      decimals="INF"
      id="ixv-58372"
      unitRef="pure">0.1045</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2021"
      decimals="INF"
      id="ixv-58373"
      unitRef="pure">-0.0153</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2022"
      decimals="INF"
      id="ixv-58374"
      unitRef="pure">-0.1671</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2023"
      decimals="INF"
      id="ixv-58375"
      unitRef="pure">0.0844</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_2024"
      decimals="INF"
      id="ixv-58376"
      unitRef="pure">0.0249</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1256">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      decimals="4"
      id="ixv-58377"
      unitRef="pure">0.1015</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1266">2020-06-30</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1271">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      decimals="4"
      id="ixv-58378"
      unitRef="pure">-0.0780</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1282">2022-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1287">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      decimals="4"
      id="ixv-58379"
      unitRef="pure">0.0674</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1297">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1302">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1308">




      Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.





      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.





      After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.



     Actual after-tax returns may differ depending on your individual circumstances.


      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).




      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableDoesReflectSalesLoads
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1311">

      Unlike the returns in the bar chart, the returns in the table reflect the maximum applicable sales charges.

     </oef:PerformanceTableDoesReflectSalesLoads>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1316">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableOneClassOfAfterTaxShown
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1321">

      After-tax returns for Class A are shown in the table below and after-tax returns for other classes will vary.

     </oef:PerformanceTableOneClassOfAfterTaxShown>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1327">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).
     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000028761_contentCd_ACBD-PRO"
      id="ixv-1331">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_01"
      id="ixv-1362">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58380"
      unitRef="pure">-0.0161</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58381"
      unitRef="pure">-0.0068</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58382"
      unitRef="pure">0.0174</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_01"
      id="ixv-1381">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58383"
      unitRef="pure">-0.0297</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58384"
      unitRef="pure">-0.0192</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributions_10"
      decimals="4"
      id="ixv-58385"
      unitRef="pure">0.0047</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-1399">
          Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58386"
      unitRef="pure">-0.0089</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58387"
      unitRef="pure">-0.0100</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088097_AfterTaxesOnDistributionsAndSales_10"
      decimals="4"
      id="ixv-58388"
      unitRef="pure">0.0079</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_01"
      id="ixv-1416">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58389"
      unitRef="pure">-0.0165</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58390"
      unitRef="pure">-0.0072</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088100_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58391"
      unitRef="pure">0.0168</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_01"
      id="ixv-1433">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58392"
      unitRef="pure">0.0073</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58393"
      unitRef="pure">-0.0063</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088099_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58394"
      unitRef="pure">0.0154</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_01"
      id="ixv-1449">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58395"
      unitRef="pure">0.0277</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58396"
      unitRef="pure">0.0041</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088101_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58397"
      unitRef="pure">0.0244</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_01"
      id="ixv-1464">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58398"
      unitRef="pure">0.0281</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58399"
      unitRef="pure">0.0053</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000205023_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteACBD-PROS000028761AAR_A_RBT_loc"
      unitRef="pure">0.0251</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_01"
      id="ixv-1479">
         Bloomberg U.S. Credit Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_01"
      decimals="4"
      id="ixv-58401"
      unitRef="pure">0.0203</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_05"
      decimals="4"
      id="ixv-58402"
      unitRef="pure">0.0023</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_ACBD-PRO_10"
      decimals="4"
      id="ixv-58403"
      unitRef="pure">0.0229</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_01"
      id="ixv-1504">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_01"
      decimals="4"
      id="ixv-58404"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_05"
      decimals="4"
      id="ixv-58405"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_ACBD-PRO_10"
      decimals="4"
      id="ixv-58406"
      unitRef="pure">0.0135</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000028761_Cid_C000205023" id="ixv-1546">2018-10-02</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8042">


     Fund Summary

     Fund:
     Fidelity&#xae; Series Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8051">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8056">


     Fidelity&#xae; Series Bond Index Fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Bloomberg U.S. Aggregate Bond Index.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8061">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8067">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8077">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000065215_contentCd_SBX-PRO"
      decimals="0"
      id="ixv-58407"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8092">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="6"
      id="ixv-58408"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="6"
      id="ixv-58409"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="6"
      id="ixv-58410"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="6"
      id="ixv-58411"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8139">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="0"
      id="ixv-58412"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="0"
      id="ixv-58413"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="0"
      id="ixv-58414"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000065215_Cid_C000211071"
      decimals="0"
      id="ixv-58415"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8196">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8201">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       55


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000065215_contentCd_SBX-PRO"
      decimals="4"
      id="ixv-58416"
      unitRef="pure">0.55</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8210">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8215">




        Normally investing at least 80% of assets in bonds included in the Bloomberg U.S. Aggregate Bond Index.

     The Bloomberg U.S. Aggregate Bond Index is a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. The index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate pass-throughs), asset-backed securities and collateralized mortgage-backed securities (agency and non-agency).

       Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Bloomberg U.S. Aggregate Bond Index using a smaller number of securities.
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-8236">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_ForeignExposureMember"
      id="ixv-8245">



      Foreign Exposure.

     Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_PrepaymentMember"
      id="ixv-8254">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-8263">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-8278">



      Correlation to Index.

     The performance of the fund and its underlying index may vary somewhat due to factors such as fees and expenses of the fund, transaction costs, sample selection, regulatory restrictions, and timing differences associated with additions to and deletions from the index. Errors in the construction or calculation of the index may occur from time to time and may not be identified and corrected for some period of time, which may have an adverse impact on the fund and its shareholders.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-8287">



      Passive Management Risk.

     The fund is managed with a passive investment strategy, attempting to track the performance of an unmanaged index of securities, regardless of the current or projected performance of the fund's index or of the actual securities included in the index. This differs from an actively managed fund, which typically seeks to outperform a benchmark index. As a result, the fund's performance could be lower than actively managed funds that may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline or a decline in the value of one or more issuers.
     The fund will be concentrated to approximately the same extent that the fund's index concentrates in the securities of issuers in a particular industry.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_LeverageRiskMember"
      id="ixv-8298">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-8308">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000065215_contentCd_SBX-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-8316">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8325">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8330">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.



     The index description appears in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level, if applicable.
     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8336">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8343">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8351">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8356">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_2020"
      decimals="INF"
      id="ixv-58417"
      unitRef="pure">0.0765</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_2021"
      decimals="INF"
      id="ixv-58418"
      unitRef="pure">-0.0180</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_2022"
      decimals="INF"
      id="ixv-58419"
      unitRef="pure">-0.1298</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_2023"
      decimals="INF"
      id="ixv-58420"
      unitRef="pure">0.0552</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_2024"
      decimals="INF"
      id="ixv-58421"
      unitRef="pure">0.0140</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8452">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000065215_contentCd_SBX-PRO"
      decimals="4"
      id="ixv-58422"
      unitRef="pure">0.0663</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8462">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8467">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000065215_contentCd_SBX-PRO"
      decimals="4"
      id="ixv-58423"
      unitRef="pure">-0.0581</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8478">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8483">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000065215_contentCd_SBX-PRO"
      decimals="4"
      id="ixv-58424"
      unitRef="pure">0.0608</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8493">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8498">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8503">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8506">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8513">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher contextRef="Pid_S000065215_contentCd_SBX-PRO" id="ixv-8518">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_01"
      id="ixv-8564">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58425"
      unitRef="pure">0.0140</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58426"
      unitRef="pure">-0.0032</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSBX-PROS000065215AAR_A_RBT_loc"
      unitRef="pure">0.0065</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_01"
      id="ixv-8581">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58428"
      unitRef="pure">-0.0008</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58429"
      unitRef="pure">-0.0142</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSBX-PROS000065215AAR_A_ATD_loc"
      unitRef="pure">-0.0046</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-8600">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58431"
      unitRef="pure">0.0082</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58432"
      unitRef="pure">-0.0068</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Cid_C000211071_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSBX-PROS000065215AAR_A_ATDS_loc"
      unitRef="pure">0.0005</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_01"
      id="ixv-8618">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_01"
      decimals="4"
      id="ixv-58434"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_05"
      decimals="4"
      id="ixv-58435"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000065215_Indexid_LB001_contentCd_SBX-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-58436"
      unitRef="pure">0.0067</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000065215_Cid_C000211071" id="ixv-8660">2019-04-26</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10247">


     Fund Summary

     Fund:
     Fidelity&#xae; U.S. Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10256">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10261">


     Fidelity&#xae; U.S. Bond Index Fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Bloomberg U.S. Aggregate Bond Index.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10266">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10272">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions, which are not reflected in the tables and examples below.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10283">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      decimals="0"
      id="ixv-58437"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10298">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="6"
      id="ixv-58438"
      unitRef="pure">0.00025</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="6"
      id="ixv-58439"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="6"
      id="ixv-58440"
      unitRef="pure">0.00000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="6"
      id="ixv-58441"
      unitRef="pure">0.00025</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10345">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="0"
      id="ixv-58442"
      unitRef="usd">3</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="0"
      id="ixv-58443"
      unitRef="usd">8</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="0"
      id="ixv-58444"
      unitRef="usd">14</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000017676_Cid_C000100043"
      decimals="0"
      id="ixv-58445"
      unitRef="usd">32</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10402">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10407">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       45


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      decimals="4"
      id="ixv-58446"
      unitRef="pure">0.45</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10416">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10421">




        Normally investing at least 80% of assets in bonds included in the Bloomberg U.S. Aggregate Bond Index.

     The Bloomberg U.S. Aggregate Bond Index is a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. The index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate pass-throughs), asset-backed securities and collateralized mortgage-backed securities (agency and non-agency).
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Bloomberg U.S. Aggregate Bond Index using a smaller number of securities.
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
      Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity&#xae; funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-10445">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_ForeignExposureMember"
      id="ixv-10454">



      Foreign Exposure.

     Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_PrepaymentMember"
      id="ixv-10463">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-10472">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-10487">



      Correlation to Index.

     The performance of the fund and its underlying index may vary somewhat due to factors such as fees and expenses of the fund, transaction costs, sample selection, regulatory restrictions, and timing differences associated with additions to and deletions from the index. Errors in the construction or calculation of the index may occur from time to time and may not be identified and corrected for some period of time, which may have an adverse impact on the fund and its shareholders.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-10496">



      Passive Management Risk.

     The fund is managed with a passive investment strategy, attempting to track the performance of an unmanaged index of securities, regardless of the current or projected performance of the fund's index or of the actual securities included in the index. This differs from an actively managed fund, which typically seeks to outperform a benchmark index. As a result, the fund's performance could be lower than actively managed funds that may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline or a decline in the value of one or more issuers.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_LeverageRiskMember"
      id="ixv-10505">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-10515">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-10523">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10532">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10537">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.



     The index description appears in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10543">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10550">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10556">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10561">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2015"
      decimals="INF"
      id="ixv-58447"
      unitRef="pure">0.0063</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2016"
      decimals="INF"
      id="ixv-58448"
      unitRef="pure">0.0251</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2017"
      decimals="INF"
      id="ixv-58449"
      unitRef="pure">0.0349</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2018"
      decimals="INF"
      id="ixv-58450"
      unitRef="pure">0.0003</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2019"
      decimals="INF"
      id="ixv-58451"
      unitRef="pure">0.0848</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2020"
      decimals="INF"
      id="ixv-58452"
      unitRef="pure">0.0780</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2021"
      decimals="INF"
      id="ixv-58453"
      unitRef="pure">-0.0179</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2022"
      decimals="INF"
      id="ixv-58454"
      unitRef="pure">-0.1304</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2023"
      decimals="INF"
      id="ixv-58455"
      unitRef="pure">0.0555</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_2024"
      decimals="INF"
      id="ixv-58456"
      unitRef="pure">0.0134</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10672">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      decimals="4"
      id="ixv-58457"
      unitRef="pure">0.0663</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10682">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10687">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      decimals="4"
      id="ixv-58458"
      unitRef="pure">-0.0588</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10698">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10703">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      decimals="4"
      id="ixv-58459"
      unitRef="pure">0.0605</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10713">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10718">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10723">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10726">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10733">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000017676_contentCd_UII-UDV-PRO"
      id="ixv-10738">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_01"
      id="ixv-10783">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58460"
      unitRef="pure">0.0134</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58461"
      unitRef="pure">-0.0031</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58462"
      unitRef="pure">0.0133</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_01"
      id="ixv-10799">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58463"
      unitRef="pure">-0.0004</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58464"
      unitRef="pure">-0.0139</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributions_10"
      decimals="4"
      id="ixv-58465"
      unitRef="pure">0.0022</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-10816">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58466"
      unitRef="pure">0.0079</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58467"
      unitRef="pure">-0.0065</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Cid_C000100043_AfterTaxesOnDistributionsAndSales_10"
      decimals="4"
      id="ixv-58468"
      unitRef="pure">0.0055</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_01"
      id="ixv-10833">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_01"
      decimals="4"
      id="ixv-58469"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_05"
      decimals="4"
      id="ixv-58470"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000017676_Indexid_LB001_contentCd_UII-UDV-PRO_10"
      decimals="4"
      id="ixv-58471"
      unitRef="pure">0.0135</oef:AvgAnnlRtrPct>
    <oef:RiskReturnHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12902">


     Fund Summary

     Fund:
     Fidelity&#xae; Series Short-Term Credit Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12911">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12916">


     Fidelity&#xae; Series Short-Term Credit Fund seeks to obtain a high level of current income consistent with the preservation of capital.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12921">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12927">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12937">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      decimals="0"
      id="ixv-58472"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12952">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="6"
      id="ixv-58473"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="6"
      id="ixv-58474"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="6"
      id="ixv-58475"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="6"
      id="ixv-58476"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-12999">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="0"
      id="ixv-58477"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="0"
      id="ixv-58478"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="0"
      id="ixv-58479"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000048583_Cid_C000153158"
      decimals="0"
      id="ixv-58480"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13056">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13061">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       67


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      decimals="4"
      id="ixv-58481"
      unitRef="pure">0.67</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13070">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13075">




        Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.

     Debt securities are used by issuers to borrow money. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security. Debt securities include corporate bonds, government securities (including Treasury securities), repurchase agreements, money market securities, mortgage and other asset-backed securities, loans and loan participations, and other securities, such as hybrids and synthetic securities, believed to have debt-like characteristics (e.g., securities classified as Tier 2 Regulatory capital, securities that rank above share capital in an insolvency waterfall, securities with maturity dates and non-cancellable interest payment structures).&#160;
     Investment grade securities in which the fund invests include securities or issuers rated at least BBB- or its equivalent by at least one nationally recognized statistical ratings organization (NRSRO), or, if unrated, determined by the Adviser to be of comparable quality.
     A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price.
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Managing the fund to have similar overall interest rate risk to the Bloomberg U.S. Credit 1-3 Years Bond Index.
      Normally maintaining a dollar-weighted average maturity of three years or less.
      Allocating assets across different market sectors and maturities.
      Investing in domestic and foreign issuers.
      Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.




   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-13109">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_ForeignExposureMember"
      id="ixv-13118">



      Foreign Exposure.

     Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_PrepaymentMember"
      id="ixv-13127">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-13136">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_LeverageRiskMember"
      id="ixv-13151">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-13161">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-13169">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13178">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13183">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.



     The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear

     in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level, if applicable.
     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13189">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13198">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13206">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13211">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2016"
      decimals="INF"
      id="ixv-58482"
      unitRef="pure">0.0155</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2017"
      decimals="INF"
      id="ixv-58483"
      unitRef="pure">0.0150</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2018"
      decimals="INF"
      id="ixv-58484"
      unitRef="pure">0.0164</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2019"
      decimals="INF"
      id="ixv-58485"
      unitRef="pure">0.0507</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2020"
      decimals="INF"
      id="ixv-58486"
      unitRef="pure">0.0414</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2021"
      decimals="INF"
      id="ixv-58487"
      unitRef="pure">-0.0027</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2022"
      decimals="INF"
      id="ixv-58488"
      unitRef="pure">-0.0307</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2023"
      decimals="INF"
      id="ixv-58489"
      unitRef="pure">0.0607</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_2024"
      decimals="INF"
      id="ixv-58490"
      unitRef="pure">0.0546</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13319">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      decimals="4"
      id="ixv-58491"
      unitRef="pure">0.0405</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13329">2020-06-30</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13334">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      decimals="4"
      id="ixv-58492"
      unitRef="pure">-0.0238</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13345">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13350">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      decimals="4"
      id="ixv-58493"
      unitRef="pure">0.0450</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13360">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13365">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13370">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13373">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13380">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000048583_contentCd_SS1-PRO"
      id="ixv-13385">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_01"
      id="ixv-13431">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58494"
      unitRef="pure">0.0546</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58495"
      unitRef="pure">0.0241</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSS1-PROS000048583AAR_A_RBT_loc"
      unitRef="pure">0.0223</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_01"
      id="ixv-13447">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58497"
      unitRef="pure">0.0386</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58498"
      unitRef="pure">0.0137</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSS1-PROS000048583AAR_A_ATD_loc"
      unitRef="pure">0.0132</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-13463">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58500"
      unitRef="pure">0.0331</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58501"
      unitRef="pure">0.0142</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Cid_C000153158_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSS1-PROS000048583AAR_A_ATDS_loc"
      unitRef="pure">0.0132</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_01"
      id="ixv-13480">
         Bloomberg U.S. Credit 1-3 Years Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_01"
      decimals="4"
      id="ixv-58503"
      unitRef="pure">0.0511</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_05"
      decimals="4"
      id="ixv-58504"
      unitRef="pure">0.0204</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_IX139_contentCd_SS1-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-58505"
      unitRef="pure">0.0213</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_01"
      id="ixv-13505">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_01"
      decimals="4"
      id="ixv-58506"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_05"
      decimals="4"
      id="ixv-58507"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000048583_Indexid_LB001_contentCd_SS1-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-58508"
      unitRef="pure">0.0123</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000048583_Cid_C000153158" id="ixv-13547">2015-03-27</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15139">


     Fund Summary

     Fund:
     Fidelity&#xae; Series Investment Grade Bond Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15148">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15153">


     Fidelity&#xae; Series Investment Grade Bond Fund seeks a high level of current income.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15158">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15164">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15174">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      decimals="0"
      id="ixv-58509"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15189">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="6"
      id="ixv-58510"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="6"
      id="ixv-58511"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="6"
      id="ixv-58512"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="6"
      id="ixv-58513"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15236">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="0"
      id="ixv-58514"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="0"
      id="ixv-58515"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="0"
      id="ixv-58516"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000023604_Cid_C000069436"
      decimals="0"
      id="ixv-58517"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15293">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15298">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       203


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      decimals="4"
      id="ixv-58518"
      unitRef="pure">2.03</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15307">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15312">




        Normally investing at least 80% of assets in investment-grade debt securities (those of medium and high quality) of all types and repurchase agreements for those securities.

     Debt securities are used by issuers to borrow money. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security. Debt securities include corporate bonds, government securities (including Treasury securities), repurchase agreements, money market securities, mortgage and other asset-backed securities, loans and loan participations, and other securities, such as hybrids and synthetic securities, believed to have debt-like characteristics (e.g., securities classified as Tier 2 Regulatory capital, securities that rank above share capital in an insolvency waterfall, securities with maturity dates and non-cancellable interest payment structures).&#160;
     Investment grade securities in which the fund invests include securities or issuers rated at least BBB- or its equivalent by at least one nationally recognized statistical ratings organization (NRSRO), or, if unrated, determined by the Adviser to be of comparable quality.
     A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price.
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Managing the fund to have similar overall interest rate risk to the Bloomberg U.S. Aggregate Bond Index.
      Allocating assets across different market sectors and maturities.
      Investing in domestic and foreign issuers.
      Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
      Potentially investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
      Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity&#xae; funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-15349">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_ForeignExposureMember"
      id="ixv-15358">



      Foreign Exposure.

     Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_PrepaymentMember"
      id="ixv-15367">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-15376">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.
     Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_LeverageRiskMember"
      id="ixv-15393">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_HighPortfolioTurnoverMember"
      id="ixv-15402">



      High Portfolio Turnover.

     High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-15412">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-15420">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15429">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15434">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.



     The index description appears in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level, if applicable.
     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15440">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15447">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15455">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15460">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2015"
      decimals="INF"
      id="ixv-58519"
      unitRef="pure">-0.0024</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2016"
      decimals="INF"
      id="ixv-58520"
      unitRef="pure">0.0435</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2017"
      decimals="INF"
      id="ixv-58521"
      unitRef="pure">0.0438</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2018"
      decimals="INF"
      id="ixv-58522"
      unitRef="pure">-0.0017</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2019"
      decimals="INF"
      id="ixv-58523"
      unitRef="pure">0.0973</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2020"
      decimals="INF"
      id="ixv-58524"
      unitRef="pure">0.0991</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2021"
      decimals="INF"
      id="ixv-58525"
      unitRef="pure">-0.0033</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2022"
      decimals="INF"
      id="ixv-58526"
      unitRef="pure">-0.1265</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2023"
      decimals="INF"
      id="ixv-58527"
      unitRef="pure">0.0679</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_2024"
      decimals="INF"
      id="ixv-58528"
      unitRef="pure">0.0215</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15573">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      decimals="4"
      id="ixv-58529"
      unitRef="pure">0.0692</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15583">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15588">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      decimals="4"
      id="ixv-58530"
      unitRef="pure">-0.0557</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15599">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15604">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      decimals="4"
      id="ixv-58531"
      unitRef="pure">0.0660</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15614">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15619">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15624">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15627">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15634">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000023604_contentCd_LIG-PRO"
      id="ixv-15639">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_01"
      id="ixv-15684">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58532"
      unitRef="pure">0.0215</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58533"
      unitRef="pure">0.0086</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58534"
      unitRef="pure">0.0220</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_01"
      id="ixv-15699">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58535"
      unitRef="pure">0.0041</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58536"
      unitRef="pure">-0.0069</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributions_10"
      decimals="4"
      id="ixv-58537"
      unitRef="pure">0.0073</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-15715">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58538"
      unitRef="pure">0.0131</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58539"
      unitRef="pure">0.0006</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Cid_C000069436_AfterTaxesOnDistributionsAndSales_10"
      decimals="4"
      id="ixv-58540"
      unitRef="pure">0.0108</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_01"
      id="ixv-15731">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_01"
      decimals="4"
      id="ixv-58541"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_05"
      decimals="4"
      id="ixv-58542"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000023604_Indexid_LB001_contentCd_LIG-PRO_10"
      decimals="4"
      id="ixv-58543"
      unitRef="pure">0.0135</oef:AvgAnnlRtrPct>
    <oef:RiskReturnHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17362">


     Fund Summary

     Fund:
     Fidelity&#xae; Series Government Money Market Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17371">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17376">


     Fidelity&#xae; Series Government Money Market Fund seeks as high a level of current income as is consistent with preservation of capital and liquidity.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17381">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17387">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17397">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      decimals="0"
      id="ixv-58544"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17412">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="6"
      id="ixv-58545"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="6"
      id="ixv-58546"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="6"
      id="ixv-58547"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="6"
      id="ixv-58548"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17459">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="0"
      id="ixv-58549"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="0"
      id="ixv-58550"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="0"
      id="ixv-58551"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000053607_Cid_C000168450"
      decimals="0"
      id="ixv-58552"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:StrategyHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17516">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17521">




        Normally investing at least 99.5% of total assets in cash, U.S. Government securities and/or repurchase agreements that are collateralized fully (i.e., collateralized by cash or government securities).
      Investing in U.S. Government securities issued by entities that are chartered or sponsored by Congress but whose securities are neither issued nor guaranteed by the U.S. Treasury.
      Investing in compliance with industry-standard regulatory requirements for money market funds for the quality, maturity, liquidity, and diversification of investments.

     In addition, the fund normally invests at least 80% of its assets in U.S. Government securities and repurchase agreements for those securities.
     U.S. Government securities are high-quality securities issued or guaranteed by the U.S. Treasury or by an agency or instrumentality of the U.S. Government. U.S. Government securities may be backed by the full faith and credit of the U.S. Treasury, the right to borrow from the U.S. Treasury, or the agency or instrumentality issuing or guaranteeing the security. Certain issuers of U.S. Government securities, including Fannie Mae, Freddie Mac, and the Federal Home Loan Banks, are sponsored or chartered by Congress but their securities are neither issued nor guaranteed by the U.S. Treasury. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security.

       A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price. A repurchase agreement entered into by the fund may be collateralized by U.S. Government securities or cash.&#160;

   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-17542">



      Interest Rate Changes.

     Interest rate increases can cause the price of a money market security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_IncomeRiskMember"
      id="ixv-17551">



      Income Risk.

     A low or negative interest rate environment can adversely affect the fund's yield.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-17560">



      Issuer-Specific Changes.

     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a money market security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_USGovernmentObligationsRiskMember"
      id="ixv-17573">




        U.S. Government Obligations Risk.

     Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-17584">


     You could lose money by investing in the fund

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskMoneyMarketFundMayNotPreserveDollarMember"
      id="ixv-17594">


     Although the fund seeks to preserve the value of your investment at $1.00 per share, it cannot guarantee it will do so

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-17604">


     An investment in the fund is not a bank account and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO_RiskMember_RiskMoneyMarketFundSponsorMayNotProvideSupportMember"
      id="ixv-17612">


     &#160;

     Fidelity

     &#160;

     Investments and its affiliates, the fund's sponsor, is not required to reimburse the fund for losses, and you should not expect that the sponsor will provide financial support to the fund at any time, including during periods of market stress.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17625">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17630">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year.



     &#160;



      Past performance is not an indication of future performance.


     The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level, if applicable.
     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17636">

      The information illustrates the changes in the performance of the fund's shares from year to year.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17643">

      Past performance is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17651">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17656">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2017"
      decimals="INF"
      id="ixv-58553"
      unitRef="pure">0.0086</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2018"
      decimals="INF"
      id="ixv-58554"
      unitRef="pure">0.0190</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2019"
      decimals="INF"
      id="ixv-58555"
      unitRef="pure">0.0227</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2020"
      decimals="INF"
      id="ixv-58556"
      unitRef="pure">0.0050</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2021"
      decimals="INF"
      id="ixv-58557"
      unitRef="pure">0.0008</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2022"
      decimals="INF"
      id="ixv-58558"
      unitRef="pure">0.0167</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2023"
      decimals="INF"
      id="ixv-58559"
      unitRef="pure">0.0522</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_2024"
      decimals="INF"
      id="ixv-58560"
      unitRef="pure">0.0537</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17759">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      decimals="4"
      id="ixv-58561"
      unitRef="pure">0.0137</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17769">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17774">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      decimals="4"
      id="ixv-58562"
      unitRef="pure">0.0002</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17784">2021-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17789">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      decimals="4"
      id="ixv-58563"
      unitRef="pure">0.0334</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17799">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000053607_contentCd_GVM-PRO"
      id="ixv-17804">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_01"
      id="ixv-17838">
         Fidelity&#xae; Series Government Money Market Fund
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58564"
      unitRef="pure">0.0537</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58565"
      unitRef="pure">0.0254</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000053607_Cid_C000168450_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteGVM-PROS000053607AAR_A_RBT_loc"
      unitRef="pure">0.0206</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000053607_Cid_C000168450" id="ixv-17869">2016-04-22</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19223">


     Fund Summary

     Fund:
     Fidelity Flex&#xae; U.S. Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19232">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19237">


     Fidelity Flex&#xae; U.S. Bond Index Fund seeks to provide investment results that correspond to the aggregate price and interest performance of the debt securities in the Bloomberg U.S. Aggregate Bond Index.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19242">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19248">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions, which are not reflected in the tables and examples below.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19259">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      decimals="0"
      id="ixv-58567"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19274">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="6"
      id="ixv-58568"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="6"
      id="ixv-58569"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="6"
      id="ixv-58570"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="6"
      id="footnoteS000056354ZUB-PROAOE_AC000177581_TE"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19329">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. This example does not include any fees paid at the fee-based account or plan level. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="0"
      id="ixv-58572"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="0"
      id="ixv-58573"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="0"
      id="ixv-58574"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000056354_Cid_C000177581"
      decimals="0"
      id="ixv-58575"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19386">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19391">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       68


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      decimals="4"
      id="ixv-58576"
      unitRef="pure">0.68</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19400">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19405">




        Normally investing at least 80% of assets in bonds included in the Bloomberg U.S. Aggregate Bond Index.

     The Bloomberg U.S. Aggregate Bond Index is a broad based, flagship benchmark that measures the investment grade, US dollar-denominated, fixed-rate taxable bond market. The index includes Treasuries, government-related and corporate securities, mortgage-backed securities (agency fixed-rate pass-throughs), asset-backed securities and collateralized mortgage-backed securities (agency and non-agency).
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Using statistical sampling techniques based on duration, maturity, interest rate sensitivity, security structure, and credit quality to attempt to replicate the returns of the Bloomberg U.S. Aggregate Bond Index using a smaller number of securities.
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
      Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity&#xae; funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-19429">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_ForeignExposureMember"
      id="ixv-19438">



      Foreign Exposure.

     Entities located in foreign countries can be affected by adverse political, regulatory, market, or economic developments in those countries.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_PrepaymentMember"
      id="ixv-19447">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-19456">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-19471">



      Correlation to Index.

     The performance of the fund and its underlying index may vary somewhat due to factors such as fees and expenses of the fund, transaction costs, sample selection, regulatory restrictions, and timing differences associated with additions to and deletions from the index. Errors in the construction or calculation of the index may occur from time to time and may not be identified and corrected for some period of time, which may have an adverse impact on the fund and its shareholders.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-19480">



      Passive Management Risk.

     The fund is managed with a passive investment strategy, attempting to track the performance of an unmanaged index of securities, regardless of the current or projected performance of the fund's index or of the actual securities included in the index. This differs from an actively managed fund, which typically seeks to outperform a benchmark index. As a result, the fund's performance could be lower than actively managed funds that may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline or a decline in the value of one or more issuers.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_LeverageRiskMember"
      id="ixv-19489">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-19499">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-19507">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19516">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19521">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.



     The index description appears in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     The performance shown does not reflect the impact of any fees paid at the fee-based account or plan level.
     Visit



      www.401k.com and log in or www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19527">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19534">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19542">

      www.401k.com and log in or www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19547">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2018"
      decimals="INF"
      id="ixv-58577"
      unitRef="pure">0.0011</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2019"
      decimals="INF"
      id="ixv-58578"
      unitRef="pure">0.0856</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2020"
      decimals="INF"
      id="ixv-58579"
      unitRef="pure">0.0772</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2021"
      decimals="INF"
      id="ixv-58580"
      unitRef="pure">-0.0189</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2022"
      decimals="INF"
      id="ixv-58581"
      unitRef="pure">-0.1296</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2023"
      decimals="INF"
      id="ixv-58582"
      unitRef="pure">0.0545</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_2024"
      decimals="INF"
      id="ixv-58583"
      unitRef="pure">0.0130</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19649">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      decimals="4"
      id="ixv-58584"
      unitRef="pure">0.0664</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19659">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19664">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      decimals="4"
      id="ixv-58585"
      unitRef="pure">-0.0579</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19675">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19680">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      decimals="4"
      id="ixv-58586"
      unitRef="pure">0.0616</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19690">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19695">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19700">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19703">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19710">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000056354_contentCd_ZUB-PRO"
      id="ixv-19715">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_01"
      id="ixv-19761">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58587"
      unitRef="pure">0.0130</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58588"
      unitRef="pure">-0.0035</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteZUB-PROS000056354AAR_A_RBT_loc"
      unitRef="pure">0.0133</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_01"
      id="ixv-19778">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58590"
      unitRef="pure">-0.0014</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58591"
      unitRef="pure">-0.0138</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteZUB-PROS000056354AAR_A_ATD_loc"
      unitRef="pure">0.0022</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-19796">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58593"
      unitRef="pure">0.0080</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58594"
      unitRef="pure">-0.0067</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Cid_C000177581_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteZUB-PROS000056354AAR_A_ATDS_loc"
      unitRef="pure">0.0056</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_01"
      id="ixv-19814">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_01"
      decimals="4"
      id="ixv-58596"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_05"
      decimals="4"
      id="ixv-58597"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000056354_Indexid_LB001_contentCd_ZUB-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-58598"
      unitRef="pure">0.0137</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000056354_Cid_C000177581" id="ixv-19856">2017-03-09</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21639">


     Fund Summary

     Fund /Class:
     Fidelity&#xae; Corporate Bond Fund
     /Fidelity&#xae; Corporate Bond Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21652">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21657">


     Fidelity&#xae; Corporate Bond Fund seeks a high level of current income.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21662">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21668">


     The following table describes the fees and expenses that may be incurred when you buy, hold, and sell shares of the fund. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

   </oef:ExpenseNarrativeTextBlock>
    <oef:ShareholderFeesCaption
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21679">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      decimals="0"
      id="ixv-58599"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21694">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="6"
      id="ixv-58600"
      unitRef="pure">0.0035</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="6"
      id="ixv-58601"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="6"
      id="ixv-58602"
      unitRef="pure">0.0010</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="6"
      id="ixv-58603"
      unitRef="pure">0.0045</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21741">


     This
     example

     helps compare the cost of investing in the fund with the cost of investing in other funds.

     Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:

   </oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="0"
      id="ixv-58604"
      unitRef="usd">46</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="0"
      id="ixv-58605"
      unitRef="usd">144</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="0"
      id="ixv-58606"
      unitRef="usd">252</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000028761_Cid_C000088096"
      decimals="0"
      id="ixv-58607"
      unitRef="usd">567</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21798">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21803">


     The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. During the most recent fiscal year, the fund's portfolio turnover rate was



       43


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      decimals="4"
      id="ixv-58608"
      unitRef="pure">0.43</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21812">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21817">




        Normally investing at least 80% of assets in corporate bonds and other corporate debt securities and repurchase agreements for those securities.

     Corporate debt securities are bonds and other debt securities issued by corporations and other business structures to borrow money. The issuer usually pays a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security. Corporate debt securities include repurchase agreements with corporate counterparties and other securities, such as hybrids and synthetic securities, believed to have corporate debt-like characteristics, (e.g., securities classified as Tier 2 Regulatory capital, securities that rank above share capital in an insolvency waterfall, securities with maturity dates and non-cancellable interest payment structures).
     A repurchase agreement is an agreement to buy a security at one price and a simultaneous agreement to sell it back at an agreed-upon price.
     Effective December 11, 2025, derivative instruments that provide investment exposure to the investments above or exposure to one or more market risk factors associated with such investments are included in the fund's 80% policy, consistent with the fund's investment policies and limitations with respect to investments in derivatives.

      &#160;
      Normally investing primarily in investment-grade corporate debt securities and repurchase agreements for those securities.
      Managing the fund to have similar overall interest rate risk to the Bloomberg U.S. Credit Bond Index.
      Investing in domestic and foreign issuers.
      Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.
      Investing in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).
      Engaging in transactions that have a leveraging effect on the fund, including investments in derivatives - such as swaps (interest rate, total return, and credit default), options, and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.
      Investing in Fidelity's Central funds (specialized investment vehicles used by Fidelity&#xae; funds to invest in particular security types or investment disciplines) consistent with the asset classes discussed above.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-21851">



      Interest Rate Changes.

     Interest rate increases can cause the price of a debt security to decrease.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_ForeignExposureMember"
      id="ixv-21860">



      Foreign Exposure.

     Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_PrepaymentMember"
      id="ixv-21869">



      Prepayment.

     The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-21878">



      Issuer-Specific Changes.

     The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole.
     A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease.
     Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_LeverageRiskMember"
      id="ixv-21895">



      Leverage Risk.

     Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-21905">


     An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency

     .


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-21913">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21922">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21927">



       The following information is intended to help you understand the risks of investing in the fund.


      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.



     The additional index has characteristics relevant to the fund's investment strategies. Index descriptions appear

     in the "Additional Index Information" section of the prospectus.



      Past performance (before and after taxes) is not an indication of future performance.


     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21933">

      The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index and an additional index over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21942">

      Past performance (before and after taxes) is not an indication of future performance.

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21948">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-21953">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2015"
      decimals="INF"
      id="ixv-58609"
      unitRef="pure">-0.0142</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2016"
      decimals="INF"
      id="ixv-58610"
      unitRef="pure">0.0649</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2017"
      decimals="INF"
      id="ixv-58611"
      unitRef="pure">0.0682</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2018"
      decimals="INF"
      id="ixv-58612"
      unitRef="pure">-0.0258</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2019"
      decimals="INF"
      id="ixv-58613"
      unitRef="pure">0.1446</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2020"
      decimals="INF"
      id="ixv-58614"
      unitRef="pure">0.1079</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2021"
      decimals="INF"
      id="ixv-58615"
      unitRef="pure">-0.0122</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2022"
      decimals="INF"
      id="ixv-58616"
      unitRef="pure">-0.1644</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2023"
      decimals="INF"
      id="ixv-58617"
      unitRef="pure">0.0879</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_2024"
      decimals="INF"
      id="ixv-58618"
      unitRef="pure">0.0282</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22066">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      decimals="4"
      id="ixv-58619"
      unitRef="pure">0.1023</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22076">2020-06-30</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22081">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      decimals="4"
      id="ixv-58620"
      unitRef="pure">-0.0773</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22092">2022-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22097">
          &#160;&#160;&#160;Year-to-Date Return
        </oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      decimals="4"
      id="ixv-58621"
      unitRef="pure">0.0700</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22107">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22112">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22117">




      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.



     Actual after-tax returns may differ depending on your individual circumstances.



      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).





      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.




   </oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22120">

      After-tax returns are calculated using the historical highest individual federal marginal income tax rates, but do not reflect the impact of state or local taxes.

     </oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22127">

      The after-tax returns shown are not relevant if you hold your shares in a retirement account or in another tax-deferred arrangement, such as an employee benefit plan (profit sharing, 401(k), or 403(b) plan).

     </oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Pid_S000028761_contentCd_CBD-PRO"
      id="ixv-22132">

      Return After Taxes on Distributions and Sale of Fund Shares may be higher than other returns for the same period due to a tax benefit of realizing a capital loss upon the sale of fund shares.

     </oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_01"
      id="ixv-22177">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-58622"
      unitRef="pure">0.0282</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-58623"
      unitRef="pure">0.0045</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-58624"
      unitRef="pure">0.0249</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_01"
      id="ixv-22192">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-58625"
      unitRef="pure">0.0130</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-58626"
      unitRef="pure">-0.0092</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributions_10"
      decimals="4"
      id="ixv-58627"
      unitRef="pure">0.0108</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-22208">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-58628"
      unitRef="pure">0.0177</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-58629"
      unitRef="pure">-0.0019</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Cid_C000088096_AfterTaxesOnDistributionsAndSales_10"
      decimals="4"
      id="ixv-58630"
      unitRef="pure">0.0131</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_01"
      id="ixv-22225">
         Bloomberg U.S. Credit Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_01"
      decimals="4"
      id="ixv-58631"
      unitRef="pure">0.0203</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_05"
      decimals="4"
      id="ixv-58632"
      unitRef="pure">0.0023</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB004_contentCd_CBD-PRO_10"
      decimals="4"
      id="ixv-58633"
      unitRef="pure">0.0229</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_01"
      id="ixv-22250">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_01"
      decimals="4"
      id="ixv-58634"
      unitRef="pure">0.0125</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_05"
      decimals="4"
      id="ixv-58635"
      unitRef="pure">-0.0033</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000028761_Indexid_LB001_contentCd_CBD-PRO_10"
      decimals="4"
      id="ixv-58636"
      unitRef="pure">0.0135</oef:AvgAnnlRtrPct>
    <link:footnoteLink
      xlink:role="http://www.xbrl.org/2003/role/link"
      xlink:type="extended">
        <link:loc
          xlink:href="#footnoteACBD-PROS000028761SHF_AC000088097"
          xlink:label="footnoteACBD-PROS000028761SHF_AC000088097"
          xlink:type="locator"/>
        <link:footnote id="footnoteACBD-PROS000028761SHF_A" xlink:label="footnoteACBD-PROS000028761SHF_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 0.75% and 0.25%, respectively.</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteACBD-PROS000028761SHF_AC000088097"
          xlink:to="footnoteACBD-PROS000028761SHF_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteACBD-PROS000028761SHF_AC000088100"
          xlink:label="footnoteACBD-PROS000028761SHF_AC000088100"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteACBD-PROS000028761SHF_AC000088100"
          xlink:to="footnoteACBD-PROS000028761SHF_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteACBD-PROS000028761SHF_BC000088099"
          xlink:label="footnoteACBD-PROS000028761SHF_BC000088099"
          xlink:type="locator"/>
        <link:footnote id="footnoteACBD-PROS000028761SHF_B" xlink:label="footnoteACBD-PROS000028761SHF_B" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">B</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">On Class C shares redeemed less than one year after purchase.</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteACBD-PROS000028761SHF_BC000088099"
          xlink:to="footnoteACBD-PROS000028761SHF_B"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000028761ACBD-PROAOE_AC000205023_FW"
          xlink:label="footnoteS000028761ACBD-PROAOE_AC000205023_FW"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000028761ACBD-PROAOE_A" xlink:label="footnoteS000028761ACBD-PROAOE_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">Fidelity Management &amp; Research Company LLC (FMR) has contractually agreed to reimburse Class Z of the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, extraordinary expenses, and acquired fund fees and expenses (including fees and expenses associated with a wholly owned subsidiary), if any, as well as non-operating expenses such as brokerage commissions and fees and expenses associated with the fund's securities lending program, if applicable), as a percentage of its average net assets, exceed 0.36% (the Expense Cap). If at any time during the current fiscal year expenses for Class Z of the fund fall below the Expense Cap, FMR reserves the right to recoup through the end of the fiscal year any expenses that were reimbursed during the current fiscal year up to, but not in excess of, the Expense Cap. This arrangement will remain in effect through </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">December 31, </xhtml:span><xhtml:span class="delClass" style="color:#ff0000; display:none;">
       </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:8.5pt; ">2026</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">. FMR may not terminate this arrangement before the expiration date without the approval of the Board of Trustees and may extend it in its discretion after that date.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteS000028761ACBD-PROAOE_AC000205023_FW"
          xlink:to="footnoteS000028761ACBD-PROAOE_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteACBD-PROS000028761AAR_A_RBT_loc"
          xlink:label="footnoteACBD-PROS000028761AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteACBD-PROS000028761AAR_A" xlink:label="footnoteACBD-PROS000028761AAR_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:4.5pt; vertical-align:3pt; ">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:8.5pt; font-style:italic; ">From </xhtml:span><xhtml:span> </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:8.5pt; font-style:italic; ">October 2, 2018</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:8.5pt; font-style:italic; ">.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteACBD-PROS000028761AAR_A_RBT_loc"
          xlink:to="footnoteACBD-PROS000028761AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSBX-PROS000065215AAR_A_RBT_loc"
          xlink:label="footnoteSBX-PROS000065215AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSBX-PROS000065215AAR_A" xlink:label="footnoteSBX-PROS000065215AAR_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">From </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">April 26, 2019</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSBX-PROS000065215AAR_A_RBT_loc"
          xlink:to="footnoteSBX-PROS000065215AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSBX-PROS000065215AAR_A_ATD_loc"
          xlink:label="footnoteSBX-PROS000065215AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSBX-PROS000065215AAR_A_ATD_loc"
          xlink:to="footnoteSBX-PROS000065215AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSBX-PROS000065215AAR_A_ATDS_loc"
          xlink:label="footnoteSBX-PROS000065215AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSBX-PROS000065215AAR_A_ATDS_loc"
          xlink:to="footnoteSBX-PROS000065215AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSS1-PROS000048583AAR_A_RBT_loc"
          xlink:label="footnoteSS1-PROS000048583AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSS1-PROS000048583AAR_A" xlink:label="footnoteSS1-PROS000048583AAR_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">From </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">March 27, 2015</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSS1-PROS000048583AAR_A_RBT_loc"
          xlink:to="footnoteSS1-PROS000048583AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSS1-PROS000048583AAR_A_ATD_loc"
          xlink:label="footnoteSS1-PROS000048583AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSS1-PROS000048583AAR_A_ATD_loc"
          xlink:to="footnoteSS1-PROS000048583AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSS1-PROS000048583AAR_A_ATDS_loc"
          xlink:label="footnoteSS1-PROS000048583AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSS1-PROS000048583AAR_A_ATDS_loc"
          xlink:to="footnoteSS1-PROS000048583AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteGVM-PROS000053607AAR_A_RBT_loc"
          xlink:label="footnoteGVM-PROS000053607AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteGVM-PROS000053607AAR_A" xlink:label="footnoteGVM-PROS000053607AAR_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">From </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">April 22, 2016</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteGVM-PROS000053607AAR_A_RBT_loc"
          xlink:to="footnoteGVM-PROS000053607AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000056354ZUB-PROAOE_AC000177581_TE"
          xlink:label="footnoteS000056354ZUB-PROAOE_AC000177581_TE"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000056354ZUB-PROAOE_A" xlink:label="footnoteS000056354ZUB-PROAOE_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">The fund is available only to certain fee-based accounts and advisory programs offered by Fidelity. Advisory account clients, retirement plans, plan sponsors and/or plan participants typically pay an advisory fee that generally covers investment advisory and administrative services.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteS000056354ZUB-PROAOE_AC000177581_TE"
          xlink:to="footnoteS000056354ZUB-PROAOE_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteZUB-PROS000056354AAR_A_RBT_loc"
          xlink:label="footnoteZUB-PROS000056354AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteZUB-PROS000056354AAR_A" xlink:label="footnoteZUB-PROS000056354AAR_A" xlink:role="http://www.xbrl.org/2003/role/footnote" xlink:type="resource" xml:lang="en-US"><xhtml:div style="padding:2px"><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:4.67pt; vertical-align:super">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">From </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">March 9, 2017</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteZUB-PROS000056354AAR_A_RBT_loc"
          xlink:to="footnoteZUB-PROS000056354AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteZUB-PROS000056354AAR_A_ATD_loc"
          xlink:label="footnoteZUB-PROS000056354AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteZUB-PROS000056354AAR_A_ATD_loc"
          xlink:to="footnoteZUB-PROS000056354AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteZUB-PROS000056354AAR_A_ATDS_loc"
          xlink:label="footnoteZUB-PROS000056354AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteZUB-PROS000056354AAR_A_ATDS_loc"
          xlink:to="footnoteZUB-PROS000056354AAR_A"
          xlink:type="arc"/>
    </link:footnoteLink>
</xbrl>
