Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Document Type	dei_DocumentType	497
Document Period End Date	dei_DocumentPeriodEndDate	Dec. 31, 2017
Registrant Name	dei_EntityRegistrantName	VANGUARD INDEX FUNDS
Central Index Key	dei_EntityCentralIndexKey	0000036405
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Mar. 25, 2019
Document Effective Date	dei_DocumentEffectiveDate	Mar. 25, 2019
Prospectus Date	rr_ProspectusDate	Apr. 25, 2018
Entity Inv Company Type	dei_EntityInvCompanyType	N-1A