v3.25.2
Shareholder Report
 6 Months Ended
Apr. 30, 2025
USD ($)
Holding
Shareholder Report [Line Items]  
Document Type N-CSRS
Amendment Flag false
Registrant Name T. ROWE PRICE SUMMIT FUNDS, INC.
Entity Central Index Key 0000912028
Entity Investment Company Type N-1A
Document Period End Date Apr. 30, 2025
C000005547  
Shareholder Report [Line Items]  
Fund Name Cash Reserves Fund
Trading Symbol TSCXX
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; 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
Cash Reserves Fund
$20
0.40%
Expenses Paid, Amount $ 20
Expense Ratio, Percent 0.40%
AssetsNet $ 5,300,085,000
Holdings Count | Holding 219
Additional Fund Statistics [Text Block]

What are some fund statistics?

Fund Statistics

Total Net Assets (000s)
$5,300,085
Number of Portfolio Holdings
219
Holdings [Text Block]

Security Allocation (as a % of Net Assets)

Variable Rate Demand Notes
20.6%
Financial Company Commercial Paper
15.3
U.S. Treasury Repurchase Agreement
13.7
Certificate of Deposit
12.9
Non-Financial Company Commercial Paper
11.4
Asset Backed Commercial Paper
7.9
U.S. Treasury Debt
6.7
U.S. Government Agency Repurchase Agreement
4.9
Other Asset Backed Securities
3.7
Short-Term and Other
2.9
Largest Holdings [Text Block]

Top Ten Holdings (as a % of Net Assets)

Federal Reserve Bank of New York
13.7%
U.S. Treasury Notes
6.7
Credit Agricole
4.9
Credit Agricole Corporate and Investment
2.0
Svenska Handelsbanken
2.0
Erste Finance Delaware
1.9
Royal Bank of Canada
1.8
Alaska HFC, State Capital Project
1.8
TotalEnergies Capital
1.6
Canadian Imperial Bank of Commerce
1.5
Material Fund Change [Text Block]
Updated Prospectus Web Address www.troweprice.com/paperless