Shareholder Report |
12 Months Ended | |||||||||
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Apr. 30, 2026
USD ($)
Holding
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| Shareholder Report [Line Items] | ||||||||||
| Document Type | N-CSR | |||||||||
| Amendment Flag | false | |||||||||
| Registrant Name | Dreyfus Institutional Reserves Funds | |||||||||
| Entity Central Index Key | 0001423799 | |||||||||
| Entity Investment Company Type | N-1A | |||||||||
| Document Period End Date | Apr. 30, 2026 | |||||||||
| C000061462 [Member] | ||||||||||
| Shareholder Report [Line Items] | ||||||||||
| Fund Name | Dreyfus Institutional Preferred Treasury Obligations Fund | |||||||||
| Class Name | Institutional Shares | |||||||||
| Trading Symbol | DNSXX | |||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Dreyfus Institutional Preferred Treasury Obligations Fund (the “Fund”) for the period of May 1, 2025 to April 30, 2026. | |||||||||
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |||||||||
| Additional Information [Text Block] | You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info@bny.com. |
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| Material Fund Change Notice [Text Block] |
This report describes changes to the Fund that occurred during the reporting period.
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| Additional Information Phone Number | 1-800-373-9387 | |||||||||
| Additional Information Email | info@bny.com | |||||||||
| Additional Information Website | www.dreyfus.com/products/mm.html#overview | |||||||||
| Expenses [Text Block] |
What were the Fund’s costs for the last year ?
(based on a hypothetical $10,000 investment)
|
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| Expenses Paid, Amount | $ 10 | [1] | ||||||||
| Expense Ratio, Percent | 0.10% | [1] | ||||||||
| Material Change Date | May 29, 2026 | |||||||||
| Net Assets | $ 777,000,000 | |||||||||
| Holdings Count | Holding | 65 | |||||||||
| Advisory Fees Paid, Amount | $ 870,381 | |||||||||
| Additional Fund Statistics [Text Block] |
KEY FUND STATISTICS (AS OF 4/30/26 )
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| Holdings [Text Block] |
Portfolio Holdings (as of 4/30/26 )
Allocation of Holdings (Based on Net Assets)
* Amount represents less than .1%.
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| Material Fund Change [Text Block] |
How has the Fund changed?
This is a summary of certain changes to the Fund since May 1, 2025 . For more complete information, you may review the Fund’s current prospectus dated August 29, 2025 as supplemented on March 13, 2026 at www.dreyfus.com/products/mm.html#overview or upon request at 1-800-373-9387.
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| Material Fund Change Name [Text Block] |
Effective on May 29, 2026, the Fund changed its name to BNY Dreyfus Institutional Preferred Treasury Obligations Fund.
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| Summary of Change Legend [Text Block] |
This is a summary of certain changes to the Fund since May 1, 2025 . For more complete information, you may review the Fund’s current prospectus dated August 29, 2025 as supplemented on March 13, 2026 at www.dreyfus.com/products/mm.html#overview or upon request at 1-800-373-9387.
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| Updated Prospectus Phone Number | 1-800-373-9387 | |||||||||
| Updated Prospectus Web Address | www.dreyfus.com/products/mm.html#overview | |||||||||
| C000061463 [Member] | ||||||||||
| Shareholder Report [Line Items] | ||||||||||
| Fund Name | Dreyfus Institutional Preferred Treasury Obligations Fund | |||||||||
| Class Name | Hamilton Shares | |||||||||
| Trading Symbol | DHLXX | |||||||||
| Annual or Semi-Annual Statement [Text Block] | This annual shareholder report contains important information about Dreyfus Institutional Preferred Treasury Obligations Fund (the “Fund”) for the period of May 1, 2025 to April 30, 2026. | |||||||||
| Shareholder Report Annual or Semi-Annual | annual shareholder report | |||||||||
| Additional Information [Text Block] | You can find additional information about the Fund at www.dreyfus.com/products/mm.html#overview. You can also request this information by calling 1-800-373-9387 (inside the U.S. only) or by sending an e-mail request to info@bny.com. |
|||||||||
| Material Fund Change Notice [Text Block] |
This report describes changes to the Fund that occurred during the reporting period.
|
|||||||||
| Additional Information Phone Number | 1-800-373-9387 | |||||||||
| Additional Information Email | info@bny.com | |||||||||
| Additional Information Website | www.dreyfus.com/products/mm.html#overview | |||||||||
| Expenses [Text Block] |
What were the Fund’s costs for the last year ?
(based on a hypothetical $10,000 investment)
|
|||||||||
| Expenses Paid, Amount | $ 15 | [2] | ||||||||
| Expense Ratio, Percent | 0.15% | [2] | ||||||||
| Material Change Date | May 29, 2026 | |||||||||
| Net Assets | $ 777,000,000 | |||||||||
| Holdings Count | Holding | 65 | |||||||||
| Advisory Fees Paid, Amount | $ 870,381 | |||||||||
| Additional Fund Statistics [Text Block] |
KEY FUND STATISTICS (AS OF 4/30/26 )
|
|||||||||
| Holdings [Text Block] |
Portfolio Holdings (as of 4/30/26 )
Allocation of Holdings (Based on Net Assets)
* Amount represents less than .1%.
|
|||||||||
| Material Fund Change [Text Block] |
How has the Fund changed?
This is a summary of certain changes to the Fund since May 1, 2025 . For more complete information, you may review the Fund’s current prospectus dated August 29, 2025 as supplemented on March 13, 2026 at www.dreyfus.com/products/mm.html#overview or upon request at 1-800-373-9387.
|
|||||||||
| Material Fund Change Name [Text Block] |
Effective on May 29, 2026, the Fund changed its name to BNY Dreyfus Institutional Preferred Treasury Obligations Fund.
|
|||||||||
| Summary of Change Legend [Text Block] |
This is a summary of certain changes to the Fund since May 1, 2025 . For more complete information, you may review the Fund’s current prospectus dated August 29, 2025 as supplemented on March 13, 2026 at www.dreyfus.com/products/mm.html#overview or upon request at 1-800-373-9387.
|
|||||||||
| Updated Prospectus Phone Number | 1-800-373-9387 | |||||||||
| Updated Prospectus Web Address | www.dreyfus.com/products/mm.html#overview | |||||||||
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