XML 13 R6.htm IDEA: XBRL DOCUMENT v3.8.0.1
Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName FIDELITY SALEM STREET TRUST
Prospectus Date rr_ProspectusDate Jun. 29, 2017
Document Creation Date dei_DocumentCreationDate Oct. 18, 2017