Document and Entity Information	Total
Prospectus:
Document Type	485BPOS
Document Period End Date	Apr. 30, 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	Aug. 25, 2020
Document Effective Date	Sep. 01, 2020
Prospectus Date	Sep. 01, 2020
Hamilton Shares Prospectus \| Dreyfus Institutional Treasury Obligations Cash Advantage Fund \| Hamilton Shares
Prospectus:
Trading Symbol	DHLXX
Hamilton Shares Prospectus \| Dreyfus Institutional Treasury Securities Cash Advantage Fund \| Hamilton Shares
Prospectus:
Trading Symbol	DHMXX
Institutional Shares Prospectus \| Dreyfus Institutional Treasury Obligations Cash Advantage Fund \| Institutional Shares
Prospectus:
Trading Symbol	DNSXX
Institutional Shares Prospectus \| Dreyfus Institutional Treasury Securities Cash Advantage Fund \| Institutional Shares
Prospectus:
Trading Symbol	DUPXX
Premier Shares Prospectus \| Dreyfus Institutional Treasury Obligations Cash Advantage Fund \| Premier Shares
Prospectus:
Trading Symbol	DRRXX
Premier Shares Prospectus \| Dreyfus Institutional Treasury Securities Cash Advantage Fund \| Premier Shares
Prospectus:
Trading Symbol	DMEXX

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation 12B
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-Section 12
-Subsection b-2

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