v3.25.2
Shareholder Report
12 Months Ended
May 31, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSR
Amendment Flag false
Registrant Name T. ROWE PRICE RESERVE INVESTMENT FUNDS, INC.
Entity Central Index Key 0001034386
Entity Investment Company Type N-1A
Document Period End Date May 31, 2025
C000005549  
Shareholder Report [Line Items]  
Fund Name Government Reserve Fund
No Trading Symbol [Flag] true
Shareholder Report Annual or Semi-Annual Annual Shareholder Report
Additional Information [Text Block] You can find the fund’s prospectus, financial information on Form N‑CSR (which includes required tax information for dividends), holdings, proxy voting information, and other information atwww.troweprice.com/prospectus. You can also request this information without charge by contacting T. Rowe Price at 1‑800‑638‑5660 or info@troweprice.com or contacting your intermediary.
Material Fund Change Notice [Text Block]  
Additional Information Phone Number 1‑800‑638‑5660
Additional Information Email <span style="box-sizing: border-box; color: rgb(0, 0, 0); display: inline; flex-wrap: nowrap; font-size: 13.3333px; font-weight: 400; grid-area: auto; line-height: 17.3333px; margin: 0px; overflow: visible; text-align: justify; text-align-last: left; white-space-collapse: preserve-breaks;">info@troweprice.com</span>
Additional Information Website www.troweprice.com/prospectus
Expenses [Text Block]

What were the fund costs for the last year? (based on a hypothetical $10,000 investment)

 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Government Reserve Fund
$0
0.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
AssetsNet $ 19,507,317,000
Holdings Count | Holding 57
Advisory Fees Paid, Amount $ 0
Additional Fund Statistics [Text Block]

What are some fund statistics?

Fund Statistics

Total Net Assets (000s)
$19,507,317
Number of Portfolio Holdings
57
Holdings [Text Block]

Security Allocation (as a % of Net Assets)

U.S. Treasury Repurchase Agreement
37.7%
U.S. Treasury Debt
31.6
U.S. Government Agency Repurchase Agreement
26.2
U.S. Government Agency Debt
5.5
Short-Term and Other
-1.0
Largest Holdings [Text Block]

Top Ten Holdings (as a % of Net Assets)

BNY Mellon
21.8%
U.S. Treasury Bills
21.5
U.S. Treasury Notes
10.1
Federal Reserve Bank of New York
9.8
RBC Dominion Securities
7.2
Citigroup Global Markets
4.8
Credit Agricole
4.6
Federal Home Loan Banks
4.5
JPMorgan Chase
3.9
State Street
2.2
Material Fund Change [Text Block]
Updated Prospectus Web Address www.troweprice.com/paperless