Label	Element	Value
Prospectus [Line Items]	rr_ProspectusLineItems
Document Type	dei_DocumentType	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Aug. 31, 2019
Entity Registrant Name	dei_EntityRegistrantName	RBB FUND, INC.
Entity Central Index Key	dei_EntityCentralIndexKey	0000831114
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Dec. 20, 2019
Document Effective Date	dei_DocumentEffectiveDate	Dec. 31, 2019
Prospectus Date	rr_ProspectusDate	Dec. 31, 2019