Document and Entity Information	Nov. 18, 2020
Prospectus:
Document Type	497
Document Period End Date	Nov. 18, 2020
Entity Registrant Name	Dreyfus Institutional Reserves Funds
Entity Central Index Key	0001423799
Entity Inv Company Type	N-1A
Amendment Flag	false
Document Creation Date	Nov. 18, 2020
Document Effective Date	Nov. 18, 2020
Prospectus Date	Jul. 31, 2020
Institutional Shares Prospectus \| Dreyfus Institutional Preferred Government Money Market Fund \| Institutional Shares
Prospectus:
Trading Symbol	DSVXX
Hamilton Shares Prospectus \| Dreyfus Institutional Preferred Government Money Market Fund \| Hamilton Shares
Prospectus:
Trading Symbol	DSHXX
Premier Shares Prospectus \| Dreyfus Institutional Preferred Government Money Market Fund \| Premier Shares
Prospectus:
Trading Symbol	DERXX

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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