<?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/20260228"
  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"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
    <link:schemaRef xlink:href="fmr-20260228.xsd" xlink:type="simple"/>
    <context id="Trust">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO_RiskMember_MunicipalMarketVolatilityMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:MunicipalMarketVolatilityMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_contentCd_SIM-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000200824Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB083Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB083Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB083Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB015Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB015Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIMunicipalIncomeFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000062002Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB015Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_GeographicExposureToEuropeMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:GeographicExposureToEuropeMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_ForeignCurrencyTransactionsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignCurrencyTransactionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_RiskNondiversifiedStatusMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNondiversifiedStatusMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_contentCd_IBI-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000214977Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXRNKMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXRNKMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXRNKMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXR6KMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXR6KMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXR6KMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXYYFMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXYYFMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXYYFMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB135Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB135Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInternationalBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000066711Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB135Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_USTreasuryObligationsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USTreasuryObligationsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_InvestingForInflationProtectionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InvestingForInflationProtectionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2016">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-01-01</startDate>
            <endDate>2016-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2017">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2017-01-01</startDate>
            <endDate>2017-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2018">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2018-01-01</startDate>
            <endDate>2018-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2019">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2019-01-01</startDate>
            <endDate>2019-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2020">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2020-01-01</startDate>
            <endDate>2020-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2021">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-01-01</startDate>
            <endDate>2021-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000113282Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_05">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_10">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelityInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000037003Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2016-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_USTreasuryObligationsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USTreasuryObligationsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_InvestingForInflationProtectionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InvestingForInflationProtectionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_contentCd_SYI-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229123Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Indexid_IXW3Z_contentCd_SYI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXW3ZMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Indexid_IXW3Z_contentCd_SYI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXW3ZMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Indexid_LB001_contentCd_SYI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072688_Indexid_LB001_contentCd_SYI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072688Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_USTreasuryObligationsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USTreasuryObligationsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_InvestingForInflationProtectionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InvestingForInflationProtectionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_contentCd_SYI-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_2022">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2022-01-01</startDate>
            <endDate>2022-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_2023">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-01-01</startDate>
            <endDate>2023-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000229124Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Indexid_IXW40_contentCd_SYI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXW40Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Indexid_IXW40_contentCd_SYI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexIXW40Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Indexid_LB001_contentCd_SYI-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000072689_Indexid_LB001_contentCd_SYI-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySeries0-55YearInflation-ProtectedBondIndexFunds-ComboPROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000072689Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2021-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ForeignExposureMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignExposureMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_GeographicExposureToEuropeMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:GeographicExposureToEuropeMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ForeignCurrencyTransactionsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ForeignCurrencyTransactionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_PrepaymentMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PrepaymentMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ContingentConvertibleSecuritiesRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:ContingentConvertibleSecuritiesRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_contentCd_ICR-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_2024">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-01-01</startDate>
            <endDate>2024-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000241080Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Indexid_LB427_contentCd_ICR-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB427Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Indexid_LB427_contentCd_ICR-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB427Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Indexid_LB135_contentCd_ICR-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB135Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000079760_Indexid_LB135_contentCd_ICR-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInternationalCreditFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000079760Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB135Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2023-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_USTreasuryObligationsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USTreasuryObligationsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_InvestingForInflationProtectionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InvestingForInflationProtectionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_contentCd_SPB-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_2025">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-01-01</startDate>
            <endDate>2025-12-31</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_ReturnBeforeTaxes_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_ReturnBeforeTaxes_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributions_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributionsAndSales_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000252148Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">oef:AfterTaxesOnDistributionsAndSalesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Indexid_LB124_contentCd_SPB-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Indexid_LB124_contentCd_SPB-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB124Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Indexid_LB001_contentCd_SPB-PRO_01">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2025-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000086560_Indexid_LB001_contentCd_SPB-PRO_AverageAnnualReturnSinceInception">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAIInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000086560Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:PerformanceMeasureAxis">fmr:IndexLB001Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2024-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_Cid_C000264609">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:ClassAxis">fmr:C000264609Member</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_InterestRateChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InterestRateChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_IssuerSpecificChangesMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:IssuerSpecificChangesMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_USTreasuryObligationsMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:USTreasuryObligationsMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_CorrelationToIndexMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:CorrelationToIndexMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_PassiveManagementRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:PassiveManagementRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_LeverageRiskMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:LeverageRiskMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_InvestingForInflationProtectionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">fmr:InvestingForInflationProtectionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskNotInsuredDepositoryInstitutionMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <context id="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_RiskLoseMoneyMember">
        <entity>
            <identifier scheme="http://www.sec.gov/CIK">0000035315</identifier>
            <segment>
                <xbrldi:explicitMember dimension="dei:DocumentInformationDocumentAxis">fmr:FidelitySAI0-5YearInflation-ProtectedBondIndexFund-PROMember</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="dei:LegalEntityAxis">fmr:S000095827Member</xbrldi:explicitMember>
                <xbrldi:explicitMember dimension="oef:RiskAxis">oef:RiskLoseMoneyMember</xbrldi:explicitMember>
            </segment>
        </entity>
        <period>
            <startDate>2026-02-28</startDate>
            <endDate>2026-02-28</endDate>
        </period>
    </context>
    <unit id="usd">
        <measure>iso4217:USD</measure>
    </unit>
    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <dei:DocumentType contextRef="Trust" id="ixv-44522">485BPOS</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="Trust" id="ixv-44523">2026-02-28</dei:DocumentPeriodEndDate>
    <dei:AmendmentFlag contextRef="Trust" id="ixv-44524">false</dei:AmendmentFlag>
    <dei:EntityCentralIndexKey contextRef="Trust" id="ixv-44525">0000035315</dei:EntityCentralIndexKey>
    <dei:EntityInvCompanyType contextRef="Trust" id="ixv-44526">N-1A</dei:EntityInvCompanyType>
    <dei:EntityRegistrantName contextRef="Trust" id="ixv-44527">Fidelity Salem Street Trust</dei:EntityRegistrantName>
    <oef:RiskReturnHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-205">


     Fund Summary

     Fund:
     Fidelity&#xae; SAI Municipal Income Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-214">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-219">


     Fidelity&#xae; SAI Municipal Income Fund seeks to provide a high current yield exempt from federal income tax.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-224">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-230">


     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_S000062002_contentCd_SIM-PRO" id="ixv-240">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000062002_contentCd_SIM-PRO"
      decimals="0"
      id="ixv-46723"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-255">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="6"
      id="ixv-46724"
      unitRef="pure">0.0033</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="6"
      id="ixv-46725"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="6"
      id="ixv-46726"
      unitRef="pure">0.0002</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="6"
      id="ixv-46727"
      unitRef="pure">0.0035</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-302">




     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_S000062002_Cid_C000200824"
      decimals="0"
      id="ixv-46728"
      unitRef="usd">36</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="0"
      id="ixv-46729"
      unitRef="usd">113</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="0"
      id="ixv-46730"
      unitRef="usd">197</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000062002_Cid_C000200824"
      decimals="0"
      id="ixv-46731"
      unitRef="usd">443</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-360">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-365">


     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



       16


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000062002_contentCd_SIM-PRO"
      decimals="4"
      id="ixv-46732"
      unitRef="pure">0.16</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-374">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-379">




        Normally investing at least 80% of assets in municipal securities whose interest is exempt from federal income tax. The municipal securities in which the fund invests are normally investment-grade (those of medium and high quality).

     Municipal debt securities are issued to raise money for a variety of public and private purposes, including general financing for state and local governments, financing for eligible non-profit organizations, or financing for a specific project or public facility. Municipal debt securities in which the fund invests include securities issued by U.S. territories and possessions, general obligation bonds of municipalities, local or state governments, project or revenue-specific bonds, or pre-refunded or escrowed bonds, municipal money market securities, and synthetic securities. Municipal securities usually pay a fixed, variable, or floating rate of interest, and must repay the amount borrowed, usually at the maturity of the security.
     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.

       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.

      Managing the fund to have similar overall interest rate risk to the supplemental index (see "Additional Index Information" section of the prospectus).
      Allocating assets across different market sectors and maturities.
      Potentially investing more than 25% of total assets in municipal securities that finance similar types of projects.
      Analyzing the credit quality of the issuer, security-specific features, current and potential future valuation, and trading opportunities to select investments.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000062002_contentCd_SIM-PRO_RiskMember_MunicipalMarketVolatilityMember"
      id="ixv-405">



      Municipal Market Volatility.

     The municipal market is volatile and can be significantly affected by adverse tax, legislative, or political changes and the financial condition of the issuers of municipal securities.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000062002_contentCd_SIM-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-414">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000062002_contentCd_SIM-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-423">



      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_S000062002_contentCd_SIM-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-435">


     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_S000062002_contentCd_SIM-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-443">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-452">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-457">



       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_S000062002_contentCd_SIM-PRO" id="ixv-463">

      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_S000062002_contentCd_SIM-PRO" id="ixv-472">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-478">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-483">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2019"
      decimals="INF"
      id="ixv-46733"
      unitRef="pure">0.0851</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2020"
      decimals="INF"
      id="ixv-46734"
      unitRef="pure">0.0427</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2021"
      decimals="INF"
      id="ixv-46735"
      unitRef="pure">0.0233</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2022"
      decimals="INF"
      id="ixv-46736"
      unitRef="pure">-0.0994</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2023"
      decimals="INF"
      id="ixv-46737"
      unitRef="pure">0.0755</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2024"
      decimals="INF"
      id="ixv-46738"
      unitRef="pure">0.0183</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_2025"
      decimals="INF"
      id="ixv-46739"
      unitRef="pure">0.0415</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-584">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000062002_contentCd_SIM-PRO"
      decimals="4"
      id="ixv-46740"
      unitRef="pure">0.0819</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-594">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-599">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000062002_contentCd_SIM-PRO"
      decimals="4"
      id="ixv-46741"
      unitRef="pure">-0.0683</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-610">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-615">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-620">




      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.



      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_S000062002_contentCd_SIM-PRO" id="ixv-623">

      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:PerformanceTableExplanationAfterTaxHigher contextRef="Pid_S000062002_contentCd_SIM-PRO" id="ixv-630">

      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_S000062002_Cid_C000200824_ReturnBeforeTaxes_01"
      id="ixv-676">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46742"
      unitRef="pure">0.0415</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-46743"
      unitRef="pure">0.0100</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSIM-PROS000062002AAR_A_RBT_loc"
      unitRef="pure">0.0279</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_01"
      id="ixv-692">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46745"
      unitRef="pure">0.0415</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-46746"
      unitRef="pure">0.0100</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSIM-PROS000062002AAR_A_ATD_loc"
      unitRef="pure">0.0274</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-708">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46748"
      unitRef="pure">0.0384</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-46749"
      unitRef="pure">0.0139</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Cid_C000200824_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSIM-PROS000062002AAR_A_ATDS_loc"
      unitRef="pure">0.0278</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_01"
      id="ixv-725">
         Bloomberg 3+ Year Municipal Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_01"
      decimals="4"
      id="ixv-46751"
      unitRef="pure">0.0430</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_05"
      decimals="4"
      id="ixv-46752"
      unitRef="pure">0.0069</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB083_contentCd_SIM-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46753"
      unitRef="pure">0.0259</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_01"
      id="ixv-750">
         Bloomberg Municipal Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_01"
      decimals="4"
      id="ixv-46754"
      unitRef="pure">0.0425</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_05"
      decimals="4"
      id="ixv-46755"
      unitRef="pure">0.0080</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000062002_Indexid_LB015_contentCd_SIM-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46756"
      unitRef="pure">0.0251</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000062002_Cid_C000200824" id="ixv-791">2018-10-02</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2335">


     Fund Summary

     Fund:
     Fidelity&#xae; International Bond Index Fund


   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2346">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2351">


     Fidelity&#xae; International Bond Index Fund seeks to provide a high level of current income.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2356">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2362">


     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_S000066711_contentCd_IBI-PRO" id="ixv-2374">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000066711_contentCd_IBI-PRO"
      decimals="0"
      id="ixv-46757"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2390">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="6"
      id="ixv-46758"
      unitRef="pure">0.0006</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="6"
      id="ixv-46759"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="6"
      id="ixv-46760"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="6"
      id="ixv-46761"
      unitRef="pure">0.0006</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2437">


     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_S000066711_Cid_C000214977"
      decimals="0"
      id="ixv-46762"
      unitRef="usd">6</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="0"
      id="ixv-46763"
      unitRef="usd">19</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="0"
      id="ixv-46764"
      unitRef="usd">34</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000066711_Cid_C000214977"
      decimals="0"
      id="ixv-46765"
      unitRef="usd">77</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2494">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2499">


     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





       64


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000066711_contentCd_IBI-PRO"
      decimals="4"
      id="ixv-46766"
      unitRef="pure">0.64</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2509">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2514">



      Normally investing at least 80% of assets in securities included in the Bloomberg Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD).

     The Bloomberg Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD) is a multi-currency benchmark that includes fixed-rate treasury, government-related, corporate and securitized bonds from developed markets issuers while excluding USD denominated debt.
     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.

      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 Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD) using a smaller number of securities.
      Hedging the fund's foreign currency exposures utilizing forward foreign currency exchange contracts.
      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_S000066711_contentCd_IBI-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-2533">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_ForeignExposureMember"
      id="ixv-2542">



      Foreign Exposure.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_GeographicExposureToEuropeMember"
      id="ixv-2553">



      Geographic Exposure to Europe.

     Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_ForeignCurrencyTransactionsMember"
      id="ixv-2562">



      Foreign Currency Transactions.

     Although a forward foreign currency exchange contract is used to reduce or hedge a fund's exposure to changes in the value of the currency, suitable hedging transactions may not be available in all circumstances, may not be successful, and may eliminate any chance for the fund to benefit from favorable fluctuations in relevant foreign currencies.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_PrepaymentMember"
      id="ixv-2571">



      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_S000066711_contentCd_IBI-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-2580">



      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_S000066711_contentCd_IBI-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-2591">



      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_S000066711_contentCd_IBI-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-2600">



      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_S000066711_contentCd_IBI-PRO_RiskMember_LeverageRiskMember"
      id="ixv-2611">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_RiskNondiversifiedStatusMember"
      id="ixv-2620">


     In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund.


   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000066711_contentCd_IBI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-2625">


     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_S000066711_contentCd_IBI-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-2633">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2642">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2647">


     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 additional indexes over various periods of time.



     The additional indexes have 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.


     Prior to September 26, 2025, the fund compared its performance to a different benchmark. The fund's historical performance may not represent its current investment policies.
     Visit



      www.fidelity.com


     for more recent performance information.

   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2652">

      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 additional indexes over various periods of time.

     </oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformancePastDoesNotIndicateFuture contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2659">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2667">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2672">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2020"
      decimals="INF"
      id="ixv-46767"
      unitRef="pure">0.0433</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2021"
      decimals="INF"
      id="ixv-46768"
      unitRef="pure">-0.0174</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2022"
      decimals="INF"
      id="ixv-46769"
      unitRef="pure">-0.1084</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2023"
      decimals="INF"
      id="ixv-46770"
      unitRef="pure">0.0748</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2024"
      decimals="INF"
      id="ixv-46771"
      unitRef="pure">0.0464</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_2025"
      decimals="INF"
      id="ixv-46772"
      unitRef="pure">0.0266</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2771">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000066711_contentCd_IBI-PRO"
      decimals="4"
      id="ixv-46773"
      unitRef="pure">0.0538</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2781">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2786">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000066711_contentCd_IBI-PRO"
      decimals="4"
      id="ixv-46774"
      unitRef="pure">-0.0461</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2797">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2802">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-2807">




      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_S000066711_contentCd_IBI-PRO" id="ixv-2810">

      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_S000066711_contentCd_IBI-PRO" id="ixv-2817">

      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_S000066711_contentCd_IBI-PRO" id="ixv-2822">

      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_S000066711_Cid_C000214977_ReturnBeforeTaxes_01"
      id="ixv-2869">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46775"
      unitRef="pure">0.0266</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-46776"
      unitRef="pure">0.0023</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteIBI-PROS000066711AAR_A_RBT_loc"
      unitRef="pure">0.0068</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_01"
      id="ixv-2885">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46778"
      unitRef="pure">0.0100</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-46779"
      unitRef="pure">-0.0074</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteIBI-PROS000066711AAR_A_ATD_loc"
      unitRef="pure">-0.0016</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-2903">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46781"
      unitRef="pure">0.0157</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-46782"
      unitRef="pure">-0.0024</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Cid_C000214977_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteIBI-PROS000066711AAR_A_ATDS_loc"
      unitRef="pure">0.0016</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_01"
      id="ixv-2921">
         Fidelity International Bond Linked Index&#x2120;
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_01"
      decimals="4"
      id="ixv-46784"
      unitRef="pure">0.0302</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_05"
      decimals="4"
      id="ixv-46785"
      unitRef="pure">0.0080</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXRNK_contentCd_IBI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46786"
      unitRef="pure">0.0120</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_01"
      id="ixv-2946">
         Bloomberg Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD)
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_01"
      decimals="4"
      id="ixv-46787"
      unitRef="pure">0.0266</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_05"
      id="footnoteIBI-PROS000066711AAR_B_BM_1_05"
      unitRef="pure"
      xsi:nil="true"/>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXR6K_contentCd_IBI-PRO_AverageAnnualReturnSinceInception"
      id="footnoteIBI-PROS000066711AAR_B_BM_1_loc"
      unitRef="pure"
      xsi:nil="true"/>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_01"
      id="ixv-2975">
         Bloomberg Global Aggregate ex-USD Float Adjusted RIC Diversified Index (Hedged USD)
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_01"
      decimals="4"
      id="ixv-46790"
      unitRef="pure">0.0300</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_05"
      decimals="4"
      id="ixv-46791"
      unitRef="pure">0.0080</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_IXYYF_contentCd_IBI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46792"
      unitRef="pure">0.0120</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_01"
      id="ixv-3000">
         Bloomberg Global Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_01"
      decimals="4"
      id="ixv-46793"
      unitRef="pure">0.0817</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_05"
      decimals="4"
      id="ixv-46794"
      unitRef="pure">-0.0215</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000066711_Indexid_LB135_contentCd_IBI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46795"
      unitRef="pure">-0.0027</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000066711_Cid_C000214977" id="ixv-3043">2019-10-10</oef:AnnualReturnInceptionDate>
    <oef:PerformanceTableMarketIndexChanged contextRef="Pid_S000066711_contentCd_IBI-PRO" id="ixv-3057">


     Effective September 26, 2025, the fund began comparing its performance to the Bloomberg Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD) rather than the Bloomberg Global Aggregate ex-USD Float Adjusted RIC Diversified Index (Hedged USD) because Fidelity Management &amp; Research Company LLC (FMR) (the Adviser) believes the Bloomberg Global Aggregate ex USD ex EM Float Adjusted RIC Diversified Index (Hedged USD) mitigates country-specific risk and volatility and also reduces currency hedging costs.

     &#160;


   </oef:PerformanceTableMarketIndexChanged>
    <oef:RiskReturnHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5040">


     Fund Summary

     Fund:
     Fidelity&#xae; Inflation-Protected Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5049">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5054">


     Fidelity&#xae; Inflation-Protected Bond Index Fund seeks to provide investment results that correspond to the total return of the inflation-protected sector of the United States Treasury market.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5059">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5065">


     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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5076">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      decimals="0"
      id="ixv-46796"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5091">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="6"
      id="ixv-46797"
      unitRef="pure">0.0005</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="6"
      id="ixv-46798"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="6"
      id="ixv-46799"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="6"
      id="ixv-46800"
      unitRef="pure">0.0005</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5138">


     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_S000037003_Cid_C000113282"
      decimals="0"
      id="ixv-46801"
      unitRef="usd">5</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="0"
      id="ixv-46802"
      unitRef="usd">16</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="0"
      id="ixv-46803"
      unitRef="usd">28</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000037003_Cid_C000113282"
      decimals="0"
      id="ixv-46804"
      unitRef="usd">64</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5195">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5200">


     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



       19


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      decimals="4"
      id="ixv-46805"
      unitRef="pure">0.19</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5209">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5214">




        Normally investing at least 80% of assets in inflation-protected debt securities included in the Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index.

     The
       Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index is a market value-weighted index that measures the performance of inflation-protected securities issued by the U.S. Treasury.

       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.

      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. Treasury Inflation-Protected Securities (TIPS) 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) and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-5238">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-5247">



      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_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_USTreasuryObligationsMember"
      id="ixv-5258">



      U.S. Treasury Obligations.

     U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-5267">



      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_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-5276">



      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_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_LeverageRiskMember"
      id="ixv-5285">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_InvestingForInflationProtectionMember"
      id="ixv-5294">



      Investing for Inflation Protection.

     Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-5304">


     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_S000037003_contentCd_PIB-I-PIB-AI-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-5312">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5321">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5326">



       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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5332">

      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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5341">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5347">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5352">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2016"
      decimals="INF"
      id="ixv-46806"
      unitRef="pure">0.0488</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2017"
      decimals="INF"
      id="ixv-46807"
      unitRef="pure">0.0298</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2018"
      decimals="INF"
      id="ixv-46808"
      unitRef="pure">-0.0137</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2019"
      decimals="INF"
      id="ixv-46809"
      unitRef="pure">0.0831</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2020"
      decimals="INF"
      id="ixv-46810"
      unitRef="pure">0.1090</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2021"
      decimals="INF"
      id="ixv-46811"
      unitRef="pure">0.0593</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2022"
      decimals="INF"
      id="ixv-46812"
      unitRef="pure">-0.1205</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2023"
      decimals="INF"
      id="ixv-46813"
      unitRef="pure">0.0378</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2024"
      decimals="INF"
      id="ixv-46814"
      unitRef="pure">0.0201</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_2025"
      decimals="INF"
      id="ixv-46815"
      unitRef="pure">0.0679</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5463">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      decimals="4"
      id="ixv-46816"
      unitRef="pure">0.0460</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5473">2016-03-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5478">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      decimals="4"
      id="ixv-46817"
      unitRef="pure">-0.0619</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5489">2022-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5494">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5499">




      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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5502">

      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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5509">

      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_S000037003_contentCd_PIB-I-PIB-AI-PRO"
      id="ixv-5514">

      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_S000037003_Cid_C000113282_ReturnBeforeTaxes_01"
      id="ixv-5559">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46818"
      unitRef="pure">0.0679</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_05"
      decimals="4"
      id="ixv-46819"
      unitRef="pure">0.0104</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_ReturnBeforeTaxes_10"
      decimals="4"
      id="ixv-46820"
      unitRef="pure">0.0303</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_01"
      id="ixv-5574">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46821"
      unitRef="pure">0.0501</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_05"
      decimals="4"
      id="ixv-46822"
      unitRef="pure">-0.0091</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributions_10"
      decimals="4"
      id="ixv-46823"
      unitRef="pure">0.0168</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-5590">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46824"
      unitRef="pure">0.0401</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_05"
      decimals="4"
      id="ixv-46825"
      unitRef="pure">-0.0004</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Cid_C000113282_AfterTaxesOnDistributionsAndSales_10"
      decimals="4"
      id="ixv-46826"
      unitRef="pure">0.0176</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_01"
      id="ixv-5607">
         Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_01"
      decimals="4"
      id="ixv-46827"
      unitRef="pure">0.0701</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_05"
      decimals="4"
      id="ixv-46828"
      unitRef="pure">0.0112</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB124_contentCd_PIB-I-PIB-AI-PRO_10"
      decimals="4"
      id="ixv-46829"
      unitRef="pure">0.0309</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_01"
      id="ixv-5632">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_01"
      decimals="4"
      id="ixv-46830"
      unitRef="pure">0.0730</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_05"
      decimals="4"
      id="ixv-46831"
      unitRef="pure">-0.0036</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000037003_Indexid_LB001_contentCd_PIB-I-PIB-AI-PRO_10"
      decimals="4"
      id="ixv-46832"
      unitRef="pure">0.0201</oef:AvgAnnlRtrPct>
    <oef:RiskReturnHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7702">


     Fund Summary

     Fund:
     Fidelity&#xae; Series 0-5 Year Inflation-Protected Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7711">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7716">


     Fidelity&#xae; Series 0-5 Year Inflation-Protected Bond Index Fund seeks to provide investment results that correspond to the total return of the inflation-protected sector of the United States Treasury market.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7721">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7727">


     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_S000072688_contentCd_SYI-PRO" id="ixv-7737">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000072688_contentCd_SYI-PRO"
      decimals="0"
      id="ixv-46833"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7752">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="6"
      id="ixv-46834"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="6"
      id="ixv-46835"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="6"
      id="ixv-46836"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="6"
      id="ixv-46837"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7799">


     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_S000072688_Cid_C000229123"
      decimals="0"
      id="ixv-46838"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="0"
      id="ixv-46839"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="0"
      id="ixv-46840"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000072688_Cid_C000229123"
      decimals="0"
      id="ixv-46841"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7856">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7861">


     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



       38


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000072688_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46842"
      unitRef="pure">0.38</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7870">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7875">




        Normally investing at least 80% of assets in inflation-protected debt securities included in the Bloomberg US Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index.
      The
        Bloomberg US Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index is a market value-weighted index that measures the performance of inflation-protected securities issued by the U.S. Treasury that have a remaining average life of less than 5 years.


       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.

      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 US Treasury Inflation-Protected Securities (TIPS) 0-5 Years 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) and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072688_contentCd_SYI-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-7898">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072688_contentCd_SYI-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-7907">



      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_S000072688_contentCd_SYI-PRO_RiskMember_USTreasuryObligationsMember"
      id="ixv-7918">



      U.S. Treasury Obligations.

     U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072688_contentCd_SYI-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-7927">



      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_S000072688_contentCd_SYI-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-7936">



      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_S000072688_contentCd_SYI-PRO_RiskMember_LeverageRiskMember"
      id="ixv-7945">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072688_contentCd_SYI-PRO_RiskMember_InvestingForInflationProtectionMember"
      id="ixv-7954">



      Investing for Inflation Protection.

     Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072688_contentCd_SYI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-7964">


     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_S000072688_contentCd_SYI-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-7972">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7981">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-7986">



       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_S000072688_contentCd_SYI-PRO" id="ixv-7992">

      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_S000072688_contentCd_SYI-PRO" id="ixv-8001">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8009">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8014">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_2022"
      decimals="INF"
      id="ixv-46843"
      unitRef="pure">-0.0284</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_2023"
      decimals="INF"
      id="ixv-46844"
      unitRef="pure">0.0465</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_2024"
      decimals="INF"
      id="ixv-46845"
      unitRef="pure">0.0486</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_2025"
      decimals="INF"
      id="ixv-46846"
      unitRef="pure">0.0599</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8106">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000072688_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46847"
      unitRef="pure">0.0300</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8116">2025-03-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8121">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000072688_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46848"
      unitRef="pure">-0.0262</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8132">2022-09-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8137">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock contextRef="Pid_S000072688_contentCd_SYI-PRO" id="ixv-8142">




      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_S000072688_contentCd_SYI-PRO" id="ixv-8145">

      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_S000072688_contentCd_SYI-PRO" id="ixv-8152">

      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_S000072688_contentCd_SYI-PRO" id="ixv-8157">

      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_S000072688_Cid_C000229123_ReturnBeforeTaxes_01"
      id="ixv-8195">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46849"
      unitRef="pure">0.0599</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072688AAR_A_RBT_loc"
      unitRef="pure">0.0314</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributions_01"
      id="ixv-8208">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46851"
      unitRef="pure">0.0429</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072688AAR_A_ATD_loc"
      unitRef="pure">0.0174</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-8221">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46853"
      unitRef="pure">0.0354</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Cid_C000229123_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072688AAR_A_ATDS_loc"
      unitRef="pure">0.0179</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072688_Indexid_IXW3Z_contentCd_SYI-PRO_01"
      id="ixv-8235">
         Bloomberg US Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Indexid_IXW3Z_contentCd_SYI-PRO_01"
      decimals="4"
      id="ixv-46855"
      unitRef="pure">0.0607</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Indexid_IXW3Z_contentCd_SYI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46856"
      unitRef="pure">0.0316</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072688_Indexid_LB001_contentCd_SYI-PRO_01"
      id="ixv-8254">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Indexid_LB001_contentCd_SYI-PRO_01"
      decimals="4"
      id="ixv-46857"
      unitRef="pure">0.0730</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072688_Indexid_LB001_contentCd_SYI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46858"
      unitRef="pure">-0.0023</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000072688_Cid_C000229123" id="ixv-8287">2021-08-13</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8331">


     Fund Summary

     Fund:
     Fidelity&#xae; Series 5+ Year Inflation-Protected Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8340">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8345">


     Fidelity&#xae; Series 5+ Year Inflation-Protected Bond Index Fund seeks to provide investment results that correspond to the total return of the inflation-protected sector of the United States Treasury market.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8350">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8356">


     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_S000072689_contentCd_SYI-PRO" id="ixv-8366">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000072689_contentCd_SYI-PRO"
      decimals="0"
      id="ixv-46859"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8381">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="6"
      id="ixv-46860"
      unitRef="pure">0.0000</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="6"
      id="ixv-46861"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="6"
      id="ixv-46862"
      unitRef="pure">0.0000</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="6"
      id="ixv-46863"
      unitRef="pure">0.0000</oef:ExpensesOverAssets>
    <oef:ExpenseExampleNarrativeTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8428">


     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_S000072689_Cid_C000229124"
      decimals="0"
      id="ixv-46864"
      unitRef="usd">0</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="0"
      id="ixv-46865"
      unitRef="usd">0</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="0"
      id="ixv-46866"
      unitRef="usd">0</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000072689_Cid_C000229124"
      decimals="0"
      id="ixv-46867"
      unitRef="usd">0</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8485">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8490">


     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



       25


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000072689_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46868"
      unitRef="pure">0.25</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8499">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8504">




        Normally investing at least 80% of assets in inflation-protected debt securities included in the Bloomberg US Treasury Inflation-Protected Securities (TIPS) 5+ Years Index.


      The
        Bloomberg US Treasury Inflation-Protected Securities (TIPS) 5+ Years Index is a market value-weighted index that measures the performance of inflation-protected securities issued by the U.S. Treasury that have a remaining average life of 5 or more years.


       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.

      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 US Treasury Inflation-Protected Securities (TIPS) 5+ Years 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) and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072689_contentCd_SYI-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-8528">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072689_contentCd_SYI-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-8537">



      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_S000072689_contentCd_SYI-PRO_RiskMember_USTreasuryObligationsMember"
      id="ixv-8548">



      U.S. Treasury Obligations.

     U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072689_contentCd_SYI-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-8557">



      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_S000072689_contentCd_SYI-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-8566">



      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_S000072689_contentCd_SYI-PRO_RiskMember_LeverageRiskMember"
      id="ixv-8575">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072689_contentCd_SYI-PRO_RiskMember_InvestingForInflationProtectionMember"
      id="ixv-8584">



      Investing for Inflation Protection.

     Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000072689_contentCd_SYI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-8594">


     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_S000072689_contentCd_SYI-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-8602">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8611">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8616">



       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_S000072689_contentCd_SYI-PRO" id="ixv-8622">

      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_S000072689_contentCd_SYI-PRO" id="ixv-8631">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8639">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8644">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_2022"
      decimals="INF"
      id="ixv-46869"
      unitRef="pure">-0.1904</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_2023"
      decimals="INF"
      id="ixv-46870"
      unitRef="pure">0.0281</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_2024"
      decimals="INF"
      id="ixv-46871"
      unitRef="pure">-0.0042</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_2025"
      decimals="INF"
      id="ixv-46872"
      unitRef="pure">0.0738</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8737">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000072689_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46873"
      unitRef="pure">0.0631</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8747">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8752">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000072689_contentCd_SYI-PRO"
      decimals="4"
      id="ixv-46874"
      unitRef="pure">-0.1042</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8763">2022-06-30</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8768">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock contextRef="Pid_S000072689_contentCd_SYI-PRO" id="ixv-8773">




      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_S000072689_contentCd_SYI-PRO" id="ixv-8776">

      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_S000072689_contentCd_SYI-PRO" id="ixv-8783">

      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_S000072689_contentCd_SYI-PRO" id="ixv-8788">

      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_S000072689_Cid_C000229124_ReturnBeforeTaxes_01"
      id="ixv-8826">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46875"
      unitRef="pure">0.0738</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072689AAR_A_RBT_loc"
      unitRef="pure">-0.0214</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributions_01"
      id="ixv-8840">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46877"
      unitRef="pure">0.0552</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072689AAR_A_ATD_loc"
      unitRef="pure">-0.0375</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-8854">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46879"
      unitRef="pure">0.0436</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Cid_C000229124_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSYI-PROS000072689AAR_A_ATDS_loc"
      unitRef="pure">-0.0228</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072689_Indexid_IXW40_contentCd_SYI-PRO_01"
      id="ixv-8869">
         Bloomberg US Treasury Inflation-Protected Securities (TIPS) 5+ Years Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Indexid_IXW40_contentCd_SYI-PRO_01"
      decimals="4"
      id="ixv-46881"
      unitRef="pure">0.0758</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Indexid_IXW40_contentCd_SYI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46882"
      unitRef="pure">-0.0205</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000072689_Indexid_LB001_contentCd_SYI-PRO_01"
      id="ixv-8889">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Indexid_LB001_contentCd_SYI-PRO_01"
      decimals="4"
      id="ixv-46883"
      unitRef="pure">0.0730</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000072689_Indexid_LB001_contentCd_SYI-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46884"
      unitRef="pure">-0.0023</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000072689_Cid_C000229124" id="ixv-8922">2021-08-13</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11480">


     Fund Summary

     Fund:
     Fidelity&#xae; SAI International Credit Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11489">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11494">


     Fidelity&#xae; SAI International Credit Fund seeks a high level of current income.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11499">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11505">


     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_S000079760_contentCd_ICR-PRO"
      id="ixv-11515">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      decimals="0"
      id="ixv-46885"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11530">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="ixv-46886"
      unitRef="pure">0.0040</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="ixv-46887"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="ixv-46888"
      unitRef="pure">0.0002</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="ixv-46889"
      unitRef="pure">0.0042</oef:ExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="footnoteS000079760ICR-PROAOE_AC000241080_FW"
      unitRef="pure">-0.0001</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="6"
      id="ixv-46891"
      unitRef="pure">0.0041</oef:NetExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11604">2027-04-30</oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11613">


     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_S000079760_Cid_C000241080"
      decimals="0"
      id="ixv-46892"
      unitRef="usd">42</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="0"
      id="ixv-46893"
      unitRef="usd">134</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="0"
      id="ixv-46894"
      unitRef="usd">234</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000079760_Cid_C000241080"
      decimals="0"
      id="ixv-46895"
      unitRef="usd">529</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11670">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11675">


     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_S000079760_contentCd_ICR-PRO"
      decimals="4"
      id="ixv-46896"
      unitRef="pure">0.55</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11684">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11689">




        Normally investing at least 80% of assets in debt securities 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;
     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.


        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.


      Normally investing primarily in securities of foreign issuers, including securities of issuers located in emerging markets. Emerging markets include countries that have an emerging stock market as defined by MSCI, countries or markets with low- to middle-income economies as classified by the World Bank, and other countries or markets that the Adviser identifies as having similar emerging markets characteristics.

     The Adviser considers a number of factors to determine whether an issuer is located in or tied economically to a particular country or region including: whether a third-party vendor has assigned a particular country or region classification to the issuer or included the issuer in an index representative of a particular country or region; the issuer's domicile, incorporation, and location of assets; whether the issuer derives at least 50% of its revenues from, or has at least 50% of its assets in, a particular country or region; the source of government guarantees (if any); and the primary trading market or listing exchange. Whether an issuer is located in or tied economically to a particular country can be determined under any of these factors.

      Normally investing primarily in investment-grade debt securities.
      Allocating investments across different market sectors, countries, and regions, including the United States.
      Investing up to 20% of assets in lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds).
      Hedging the fund's foreign currency exposures utilizing forward foreign currency exchange contracts.
      Investing in contingent convertible securities.
      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_S000079760_contentCd_ICR-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-11728">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ForeignExposureMember"
      id="ixv-11737">



      Foreign Exposure.

     Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market.
     The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors.
     Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile.
     Foreign exchange rates also can be extremely volatile.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_GeographicExposureToEuropeMember"
      id="ixv-11752">



      Geographic Exposure to Europe.

     Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ForeignCurrencyTransactionsMember"
      id="ixv-11761">



      Foreign Currency Transactions.

     Although a forward foreign currency exchange contract is used to reduce or hedge a fund's exposure to changes in the value of the currency, suitable hedging transactions may not be available in all circumstances, may not be successful, and may eliminate any chance for the fund to benefit from favorable fluctuations in relevant foreign currencies.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_PrepaymentMember"
      id="ixv-11770">



      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_S000079760_contentCd_ICR-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-11779">



      Issuer-Specific Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_ContingentConvertibleSecuritiesRiskMember"
      id="ixv-11792">



      Contingent Convertible Securities Risk.

     Contingent convertible securities have unique equity conversion or principal write-down features that involve additional risks, which may include cancellation of interest payments by the issuer or a regulatory authority; subordination to other creditors due to either a liquidation or other bankruptcy-related event or a conversion of the security from debt to equity; and a write-down of the security's principal amount.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_LeverageRiskMember"
      id="ixv-11801">



      Leverage Risk.

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



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-11811">


     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_S000079760_contentCd_ICR-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-11819">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11828">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11833">



       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_S000079760_contentCd_ICR-PRO"
      id="ixv-11839">

      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_S000079760_contentCd_ICR-PRO"
      id="ixv-11850">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11856">

      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11861">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_2024"
      decimals="INF"
      id="ixv-46897"
      unitRef="pure">0.0619</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_2025"
      decimals="INF"
      id="ixv-46898"
      unitRef="pure">0.0640</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11946">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      decimals="4"
      id="ixv-46899"
      unitRef="pure">0.0498</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11956">2024-09-30</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11961">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      decimals="4"
      id="ixv-46900"
      unitRef="pure">-0.0069</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11972">2024-12-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11977">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000079760_contentCd_ICR-PRO"
      id="ixv-11982">




      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_S000079760_contentCd_ICR-PRO"
      id="ixv-11985">

      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_S000079760_contentCd_ICR-PRO"
      id="ixv-11992">

      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_S000079760_contentCd_ICR-PRO"
      id="ixv-11997">

      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_S000079760_Cid_C000241080_ReturnBeforeTaxes_01"
      id="ixv-12035">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46901"
      unitRef="pure">0.0640</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteICR-PROS000079760AAR_A_RBT_loc"
      unitRef="pure">0.0664</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributions_01"
      id="ixv-12048">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46903"
      unitRef="pure">0.0465</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteICR-PROS000079760AAR_A_ATD_loc"
      unitRef="pure">0.0498</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-12061">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46905"
      unitRef="pure">0.0383</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Cid_C000241080_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteICR-PROS000079760AAR_A_ATDS_loc"
      unitRef="pure">0.0441</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000079760_Indexid_LB427_contentCd_ICR-PRO_01"
      id="ixv-12075">
         Bloomberg Global Aggregate Credit Ex U.S. Index (Hedged USD)
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Indexid_LB427_contentCd_ICR-PRO_01"
      decimals="4"
      id="ixv-46907"
      unitRef="pure">0.0636</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Indexid_LB427_contentCd_ICR-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46908"
      unitRef="pure">0.0666</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000079760_Indexid_LB135_contentCd_ICR-PRO_01"
      id="ixv-12094">
         Bloomberg Global Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Indexid_LB135_contentCd_ICR-PRO_01"
      decimals="4"
      id="ixv-46909"
      unitRef="pure">0.0817</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000079760_Indexid_LB135_contentCd_ICR-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46910"
      unitRef="pure">0.0432</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000079760_Cid_C000241080" id="ixv-12126">2023-03-01</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13480">


     Fund Summary

     Fund:
     Fidelity&#xae; SAI Inflation-Protected Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13489">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13494">


     Fidelity&#xae; SAI Inflation-Protected Bond Index Fund seeks to provide investment results that correspond to the total return of the inflation-protected sector of the United States Treasury market.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13499">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13505">


     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_S000086560_contentCd_SPB-PRO"
      id="ixv-13515">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      decimals="0"
      id="ixv-46911"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13530">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="ixv-46912"
      unitRef="pure">0.0005</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="ixv-46913"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="ixv-46914"
      unitRef="pure">0.0001</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="ixv-46915"
      unitRef="pure">0.0006</oef:ExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="footnoteS000086560SPB-PROAOE_AC000252148_FW"
      unitRef="pure">-0.0001</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="6"
      id="ixv-46917"
      unitRef="pure">0.0005</oef:NetExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13607">2027-04-30</oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13616">


     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_S000086560_Cid_C000252148"
      decimals="0"
      id="ixv-46918"
      unitRef="usd">5</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="0"
      id="ixv-46919"
      unitRef="usd">18</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="0"
      id="ixv-46920"
      unitRef="usd">33</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Pid_S000086560_Cid_C000252148"
      decimals="0"
      id="ixv-46921"
      unitRef="usd">76</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13673">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13678">


     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



       34


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      decimals="4"
      id="ixv-46922"
      unitRef="pure">0.34</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13687">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13692">




        Normally investing at least 80% of assets in inflation-protected debt securities included in the Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index.

     The
       Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index is a market value-weighted index that measures the performance of inflation-protected securities issued by the U.S. Treasury.

       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.

      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. Treasury Inflation-Protected Securities (TIPS) 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) and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-13715">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-13724">



      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_S000086560_contentCd_SPB-PRO_RiskMember_USTreasuryObligationsMember"
      id="ixv-13735">



      U.S. Treasury Obligations.

     U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-13744">



      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_S000086560_contentCd_SPB-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-13753">



      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_S000086560_contentCd_SPB-PRO_RiskMember_LeverageRiskMember"
      id="ixv-13762">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO_RiskMember_InvestingForInflationProtectionMember"
      id="ixv-13771">



      Investing for Inflation Protection.

     Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-13781">


     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_S000086560_contentCd_SPB-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-13789">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13798">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13803">



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


      The information illustrates the performance of the fund's shares over the past 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_S000086560_contentCd_SPB-PRO"
      id="ixv-13809">

      The information illustrates the performance of the fund's shares over the past 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_S000086560_contentCd_SPB-PRO"
      id="ixv-13814">

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

     </oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13820">



      www.fidelity.com
     </oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13826">


     Year-by-Year Returns

   </oef:BarChartHeading>
    <oef:AnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_2025"
      decimals="INF"
      id="ixv-46923"
      unitRef="pure">0.0676</oef:AnnlRtrPct>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13908">
          &#160;&#160;&#160;Highest Quarter Return
        </oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      decimals="4"
      id="ixv-46924"
      unitRef="pure">0.0417</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13918">2025-03-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13923">
          &#160;&#160;&#160;Lowest Quarter Return
        </oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      decimals="4"
      id="ixv-46925"
      unitRef="pure">-0.0009</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13934">2025-12-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:PerformanceTableHeading
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13939">


     Average Annual Returns


   </oef:PerformanceTableHeading>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Pid_S000086560_contentCd_SPB-PRO"
      id="ixv-13944">




      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_S000086560_contentCd_SPB-PRO"
      id="ixv-13947">

      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_S000086560_contentCd_SPB-PRO"
      id="ixv-13954">

      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_S000086560_contentCd_SPB-PRO"
      id="ixv-13959">

      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_S000086560_Cid_C000252148_ReturnBeforeTaxes_01"
      id="ixv-13998">
         Return Before Taxes
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_ReturnBeforeTaxes_01"
      decimals="4"
      id="ixv-46926"
      unitRef="pure">0.0676</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_ReturnBeforeTaxes_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSPB-PROS000086560AAR_A_RBT_loc"
      unitRef="pure">0.0409</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributions_01"
      id="ixv-14011">
         Return After Taxes on Distributions
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributions_01"
      decimals="4"
      id="ixv-46928"
      unitRef="pure">0.0499</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributions_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSPB-PROS000086560AAR_A_ATD_loc"
      unitRef="pure">0.0266</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributionsAndSales_01"
      id="ixv-14024">
         Return After Taxes on Distributions and Sale of Fund Shares
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributionsAndSales_01"
      decimals="4"
      id="ixv-46930"
      unitRef="pure">0.0400</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Cid_C000252148_AfterTaxesOnDistributionsAndSales_AverageAnnualReturnSinceInception"
      decimals="4"
      id="footnoteSPB-PROS000086560AAR_A_ATDS_loc"
      unitRef="pure">0.0252</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000086560_Indexid_LB124_contentCd_SPB-PRO_01"
      id="ixv-14038">
         Bloomberg U.S. Treasury Inflation-Protected Securities (TIPS) Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Indexid_LB124_contentCd_SPB-PRO_01"
      decimals="4"
      id="ixv-46932"
      unitRef="pure">0.0701</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Indexid_LB124_contentCd_SPB-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46933"
      unitRef="pure">0.0433</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Pid_S000086560_Indexid_LB001_contentCd_SPB-PRO_01"
      id="ixv-14057">
         Bloomberg U.S. Aggregate Bond Index
        </oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Indexid_LB001_contentCd_SPB-PRO_01"
      decimals="4"
      id="ixv-46934"
      unitRef="pure">0.0730</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Pid_S000086560_Indexid_LB001_contentCd_SPB-PRO_AverageAnnualReturnSinceInception"
      decimals="4"
      id="ixv-46935"
      unitRef="pure">0.0402</oef:AvgAnnlRtrPct>
    <oef:AnnualReturnInceptionDate contextRef="Pid_S000086560_Cid_C000252148" id="ixv-14089">2024-08-16</oef:AnnualReturnInceptionDate>
    <oef:RiskReturnHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15319">


     Fund Summary

     Fund:
     Fidelity&#xae; SAI 0-5 Year Inflation-Protected Bond Index Fund

   </oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15328">


     Investment Objective


   </oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15333">


     Fidelity&#xae; SAI 0-5 Year Inflation-Protected Bond Index Fund seeks to provide investment results that correspond to the total return of the inflation-protected sector of the United States Treasury market.


   </oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15338">


     Fee Table


   </oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15344">


     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_S000095827_contentCd_IPBI-PRO"
      id="ixv-15354">


     Shareholder fees


   </oef:ShareholderFeesCaption>
    <oef:ShareholderFeeOther
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      decimals="0"
      id="ixv-46936"
      unitRef="usd">0</oef:ShareholderFeeOther>
    <oef:OperatingExpensesCaption
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15369">


     Annual Operating Expenses


   </oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="ixv-46937"
      unitRef="pure">0.0005</oef:ManagementFeesOverAssets>
    <oef:DistributionAndService12b1FeesOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="ixv-46938"
      unitRef="pure">0</oef:DistributionAndService12b1FeesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="footnoteS000095827IPBI-PROAOE_AC000264609_OE"
      unitRef="pure">0.0006</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="ixv-46940"
      unitRef="pure">0.0011</oef:ExpensesOverAssets>
    <oef:FeeWaiverOrReimbursementOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="footnoteS000095827IPBI-PROAOE_BC000264609_FW"
      unitRef="pure">-0.0006</oef:FeeWaiverOrReimbursementOverAssets>
    <oef:NetExpensesOverAssets
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="6"
      id="ixv-46942"
      unitRef="pure">0.0005</oef:NetExpensesOverAssets>
    <oef:OtherExpensesNewFundBasedOnEstimates
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15443">

      Based on estimated amounts for the current fiscal year.

     </oef:OtherExpensesNewFundBasedOnEstimates>
    <oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15454">2027-04-30</oef:FeeWaiverOrReimbursementOverAssetsDateOfTermination>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15461">


     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_S000095827_Cid_C000264609"
      decimals="0"
      id="ixv-46943"
      unitRef="usd">5</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Pid_S000095827_Cid_C000264609"
      decimals="0"
      id="ixv-46944"
      unitRef="usd">27</oef:ExpenseExampleYear03>
    <oef:PortfolioTurnoverHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15500">


     Portfolio Turnover


   </oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15505">


     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. For the period from November 4, 2025 to December 31, 2025, the fund's portfolio turnover rate was



       1


     % of the average value of its portfolio.


   </oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      decimals="4"
      id="ixv-46945"
      unitRef="pure">0.01</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15514">


     Principal Investment Strategies


   </oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15519">




        Normally investing at least 80% of assets in inflation-protected debt securities included in the Bloomberg US Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index.

     The Bloomberg US Treasury Inflation-Protected Securities (TIPS) 0-5 Years Index is a market value-weighted index that measures the performance of inflation-protected securities issued by the U.S. Treasury that have a remaining average life of less than 5 years.

       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.

      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 US Treasury Inflation-Protected Securities (TIPS) 0-5 Years 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) and futures contracts - and forward-settling securities, to adjust the fund's risk exposure.


   </oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_InterestRateChangesMember"
      id="ixv-15541">



      Interest Rate Changes.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_IssuerSpecificChangesMember"
      id="ixv-15550">



      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_S000095827_contentCd_IPBI-PRO_RiskMember_USTreasuryObligationsMember"
      id="ixv-15561">



      U.S. Treasury Obligations.

     U.S. Treasury obligations are high-quality securities issued or guaranteed by the U.S. Treasury providing minimal risk of loss of principal if held to maturity. Fluctuations in interest rates may cause the market value of such securities to vary.

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_CorrelationToIndexMember"
      id="ixv-15570">



      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_S000095827_contentCd_IPBI-PRO_RiskMember_PassiveManagementRiskMember"
      id="ixv-15579">



      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_S000095827_contentCd_IPBI-PRO_RiskMember_LeverageRiskMember"
      id="ixv-15588">



      Leverage Risk.

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

   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_InvestingForInflationProtectionMember"
      id="ixv-15597">



      Investing for Inflation Protection.

     Increases in real interest rates can cause the price of inflation-protected debt securities to decrease. Interest payments on inflation-protected debt securities can be unpredictable.



   </oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO_RiskMember_RiskNotInsuredDepositoryInstitutionMember"
      id="ixv-15607">


     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_S000095827_contentCd_IPBI-PRO_RiskMember_RiskLoseMoneyMember"
      id="ixv-15615">


     &#160;

     You could lose money by investing in the fund.


   </oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15624">


     Performance


   </oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15629">






      Performance history will be available for the fund after the fund has been in operation for one calendar year.



   </oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceOneYearOrLess
      contextRef="Pid_S000095827_contentCd_IPBI-PRO"
      id="ixv-15633">

      Performance history will be available for the fund after the fund has been in operation for one calendar year.

     </oef:PerformanceOneYearOrLess>
    <link:footnoteLink
      xlink:role="http://www.xbrl.org/2003/role/link"
      xlink:type="extended">
        <link:loc
          xlink:href="#footnoteSIM-PROS000062002AAR_A_RBT_loc"
          xlink:label="footnoteSIM-PROS000062002AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSIM-PROS000062002AAR_A" xlink:label="footnoteSIM-PROS000062002AAR_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">October 2, 2018</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="footnoteSIM-PROS000062002AAR_A_RBT_loc"
          xlink:to="footnoteSIM-PROS000062002AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSIM-PROS000062002AAR_A_ATD_loc"
          xlink:label="footnoteSIM-PROS000062002AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSIM-PROS000062002AAR_A_ATD_loc"
          xlink:to="footnoteSIM-PROS000062002AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSIM-PROS000062002AAR_A_ATDS_loc"
          xlink:label="footnoteSIM-PROS000062002AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSIM-PROS000062002AAR_A_ATDS_loc"
          xlink:to="footnoteSIM-PROS000062002AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteIBI-PROS000066711AAR_A_RBT_loc"
          xlink:label="footnoteIBI-PROS000066711AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteIBI-PROS000066711AAR_A" xlink:label="footnoteIBI-PROS000066711AAR_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 10, 2019</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="footnoteIBI-PROS000066711AAR_A_RBT_loc"
          xlink:to="footnoteIBI-PROS000066711AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteIBI-PROS000066711AAR_A_ATD_loc"
          xlink:label="footnoteIBI-PROS000066711AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteIBI-PROS000066711AAR_A_ATD_loc"
          xlink:to="footnoteIBI-PROS000066711AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteIBI-PROS000066711AAR_A_ATDS_loc"
          xlink:label="footnoteIBI-PROS000066711AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteIBI-PROS000066711AAR_A_ATDS_loc"
          xlink:to="footnoteIBI-PROS000066711AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteIBI-PROS000066711AAR_B_BM_1_05"
          xlink:label="footnoteIBI-PROS000066711AAR_B_BM_1_05"
          xlink:type="locator"/>
        <link:footnote id="footnoteIBI-PROS000066711AAR_B" xlink:label="footnoteIBI-PROS000066711AAR_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
      class="redlineClass"
      style="font-family:Arial; font-size:4.5pt; vertical-align:3pt; ">B</xhtml:span><xhtml:span> </xhtml:span><xhtml:span
      class="redlineClass"
      style="font-family:Arial; font-size:8.5pt; font-style:italic; ">The inception date for the index was after the fund commenced operations, and returns for this time period are not yet available.</xhtml:span><xhtml:span> </xhtml:span></xhtml:div></link:footnote>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteIBI-PROS000066711AAR_B_BM_1_05"
          xlink:to="footnoteIBI-PROS000066711AAR_B"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteIBI-PROS000066711AAR_B_BM_1_loc"
          xlink:label="footnoteIBI-PROS000066711AAR_B_BM_1_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteIBI-PROS000066711AAR_B_BM_1_loc"
          xlink:to="footnoteIBI-PROS000066711AAR_B"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072688AAR_A_RBT_loc"
          xlink:label="footnoteSYI-PROS000072688AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSYI-PROS000072688AAR_A" xlink:label="footnoteSYI-PROS000072688AAR_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">August 13, 2021</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="footnoteSYI-PROS000072688AAR_A_RBT_loc"
          xlink:to="footnoteSYI-PROS000072688AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072688AAR_A_ATD_loc"
          xlink:label="footnoteSYI-PROS000072688AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSYI-PROS000072688AAR_A_ATD_loc"
          xlink:to="footnoteSYI-PROS000072688AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072688AAR_A_ATDS_loc"
          xlink:label="footnoteSYI-PROS000072688AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSYI-PROS000072688AAR_A_ATDS_loc"
          xlink:to="footnoteSYI-PROS000072688AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072689AAR_A_RBT_loc"
          xlink:label="footnoteSYI-PROS000072689AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSYI-PROS000072689AAR_A" xlink:label="footnoteSYI-PROS000072689AAR_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">August 13, 2021</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="footnoteSYI-PROS000072689AAR_A_RBT_loc"
          xlink:to="footnoteSYI-PROS000072689AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072689AAR_A_ATD_loc"
          xlink:label="footnoteSYI-PROS000072689AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSYI-PROS000072689AAR_A_ATD_loc"
          xlink:to="footnoteSYI-PROS000072689AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSYI-PROS000072689AAR_A_ATDS_loc"
          xlink:label="footnoteSYI-PROS000072689AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSYI-PROS000072689AAR_A_ATDS_loc"
          xlink:to="footnoteSYI-PROS000072689AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000079760ICR-PROAOE_AC000241080_FW"
          xlink:label="footnoteS000079760ICR-PROAOE_AC000241080_FW"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000079760ICR-PROAOE_A" xlink:label="footnoteS000079760ICR-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">Fidelity Management &amp; Research Company LLC (FMR) has contractually agreed to reimburse the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, proxy and shareholder meeting expenses, 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 0.41% (the Expense Cap). If at any time during the current fiscal year expenses for 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; font-style:italic">April 30, </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; font-style:italic; ">2027</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt; font-style:italic">. 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="footnoteS000079760ICR-PROAOE_AC000241080_FW"
          xlink:to="footnoteS000079760ICR-PROAOE_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteICR-PROS000079760AAR_A_RBT_loc"
          xlink:label="footnoteICR-PROS000079760AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteICR-PROS000079760AAR_A" xlink:label="footnoteICR-PROS000079760AAR_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:4.5pt; vertical-align:3pt">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 1, 2023</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="footnoteICR-PROS000079760AAR_A_RBT_loc"
          xlink:to="footnoteICR-PROS000079760AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteICR-PROS000079760AAR_A_ATD_loc"
          xlink:label="footnoteICR-PROS000079760AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteICR-PROS000079760AAR_A_ATD_loc"
          xlink:to="footnoteICR-PROS000079760AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteICR-PROS000079760AAR_A_ATDS_loc"
          xlink:label="footnoteICR-PROS000079760AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteICR-PROS000079760AAR_A_ATDS_loc"
          xlink:to="footnoteICR-PROS000079760AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000086560SPB-PROAOE_AC000252148_FW"
          xlink:label="footnoteS000086560SPB-PROAOE_AC000252148_FW"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000086560SPB-PROAOE_A" xlink:label="footnoteS000086560SPB-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 class="delClass" style="color:#ff0000; display:none;">
      </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 style="font-family:Arial; font-size:8.5pt">Fidelity Management &amp; Research Company LLC (FMR) has contractually agreed to reimburse the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, proxy and shareholder meeting expenses, 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</xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">0.05% (the Expense Cap). If at any time during the current fiscal year expenses for 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">April 30, </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; font-style:italic; ">2027</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="footnoteS000086560SPB-PROAOE_AC000252148_FW"
          xlink:to="footnoteS000086560SPB-PROAOE_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSPB-PROS000086560AAR_A_RBT_loc"
          xlink:label="footnoteSPB-PROS000086560AAR_A_RBT_loc"
          xlink:type="locator"/>
        <link:footnote id="footnoteSPB-PROS000086560AAR_A" xlink:label="footnoteSPB-PROS000086560AAR_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; ">August 16, 2024</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="footnoteSPB-PROS000086560AAR_A_RBT_loc"
          xlink:to="footnoteSPB-PROS000086560AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSPB-PROS000086560AAR_A_ATD_loc"
          xlink:label="footnoteSPB-PROS000086560AAR_A_ATD_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSPB-PROS000086560AAR_A_ATD_loc"
          xlink:to="footnoteSPB-PROS000086560AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteSPB-PROS000086560AAR_A_ATDS_loc"
          xlink:label="footnoteSPB-PROS000086560AAR_A_ATDS_loc"
          xlink:type="locator"/>
        <link:footnoteArc
          xlink:arcrole="http://www.xbrl.org/2003/arcrole/fact-footnote"
          xlink:from="footnoteSPB-PROS000086560AAR_A_ATDS_loc"
          xlink:to="footnoteSPB-PROS000086560AAR_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000095827IPBI-PROAOE_AC000264609_OE"
          xlink:label="footnoteS000095827IPBI-PROAOE_AC000264609_OE"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000095827IPBI-PROAOE_A" xlink:label="footnoteS000095827IPBI-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:4.5pt; vertical-align:3pt">A</xhtml:span><xhtml:span> </xhtml:span><xhtml:span> </xhtml:span><xhtml:span style="font-family:Arial; font-size:8.5pt">Based on estimated amounts for the current fiscal year.</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="footnoteS000095827IPBI-PROAOE_AC000264609_OE"
          xlink:to="footnoteS000095827IPBI-PROAOE_A"
          xlink:type="arc"/>
        <link:loc
          xlink:href="#footnoteS000095827IPBI-PROAOE_BC000264609_FW"
          xlink:label="footnoteS000095827IPBI-PROAOE_BC000264609_FW"
          xlink:type="locator"/>
        <link:footnote id="footnoteS000095827IPBI-PROAOE_B" xlink:label="footnoteS000095827IPBI-PROAOE_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:4.5pt; vertical-align:3pt">B</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 the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, proxy and shareholder meeting expenses, 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 0.05% (the Expense Cap). If at any time during the current fiscal year expenses for 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">April 30, 2027</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="footnoteS000095827IPBI-PROAOE_BC000264609_FW"
          xlink:to="footnoteS000095827IPBI-PROAOE_B"
          xlink:type="arc"/>
    </link:footnoteLink>
</xbrl>
