v3.25.2
Shareholder Report
6 Months Ended
Jun. 30, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
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 Jun. 30, 2025
C000224086  
Shareholder Report [Line Items]  
Fund Name Transition Fund
No Trading Symbol [Flag] true
Annual or Semi-Annual Statement [Text Block]

This semi-annual shareholder report contains important information about Transition Fund (the "fund") for the period of January 1, 2025 to June 30, 2025. 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. 

Shareholder Report Annual or Semi-Annual Semi-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 six months? (based on a hypothetical $10,000 investment)

 
Costs of a $10,000 investment
Costs paid as a percentage of a $10,000 investment
Transition Fund
$0
0.00%
Expenses Paid, Amount $ 0
Expense Ratio, Percent 0.00%
Updated Performance Information Location [Text Block]

If you invest directly with T. Rowe Price, you can elect to receive future shareholder reports or other important documents through electronic delivery by enrolling at www.troweprice.com/paperless. If you invest through a financial intermediary such as an investment advisor, a bank, retirement plan sponsor or a brokerage firm, please contact that organization and ask if it can provide electronic delivery.

Visit www.troweprice.com/en/us/market-data-disclosures for additional legal notices & disclaimers.

AssetsNet $ 22,308,000
Holdings Count | Holding 1
InvestmentCompanyPortfolioTurnover 0.00%
Additional Fund Statistics [Text Block]

What are some fund statistics?

Fund Statistics

Total Net Assets (000s)
$22,308
Number of Portfolio Holdings
1
Additional Fund Statistics Significance or Limits [Text Block]
Portfolio Turnover Rate
-%
Holdings [Text Block]

Security Allocation (as a % of Net Assets)

Money Market Funds
100.0%
Short-Term and Other
-%
Largest Holdings [Text Block]

Top Ten Holdings (as a % of Net Assets)

T. Rowe Price U.S. Treasury Money Fund
100.0%
Material Fund Change [Text Block]
Updated Prospectus Web Address www.troweprice.com/paperless