v3.26.1
Label Element Value
Risk/Return: oef_RiskReturnAbstract  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Apr. 30, 2026
Registrant Name dei_EntityRegistrantName Dreyfus Institutional Reserves Funds
Entity Central Index Key dei_EntityCentralIndexKey 0001423799
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate Aug. 27, 2026
Document Effective Date dei_DocumentEffectiveDate Aug. 31, 2026
Entity Investment Company Type dei_EntityInvCompanyType N-1A
Prospectus Date oef_ProspectusDate Aug. 31, 2026
Prospectus Summary | BNY Dreyfus Institutional Preferred Treasury Obligations Fund | Hamilton Shares  
Risk/Return: oef_RiskReturnAbstract  
Trading Symbol dei_TradingSymbol DHLXX