2.4.0.6 Html 2 9 1 false 2 0 false 0 false false R1.htm 0100113 - Document - Risk/Return Summary {Unlabeled} Sheet http://fidelity.com/role/RiskReturnSummarySpartanUSBondIndexFundInvestorFidelityAdvantageClass Risk/Return Summary false false R2.htm 040000 - Disclosure - Risk/Return Detail Data {Elements} Sheet http://xbrl.sec.gov/rr/role/RiskReturnDetailData Risk/Return Detail Data true false All Reports Book All Reports fsst35315-20111029.xml fsst35315-20111029.xsd fsst35315-20111029_cal.xml fsst35315-20111029_def.xml fsst35315-20111029_lab.xml fsst35315-20111029_pre.xml true true