v3.26.1
Shareholder Report
 6 Months Ended
Apr. 30, 2026
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, 2026
Shareholder Report Annual or Semi-Annual Semi-Annual Shareholder Report
C000005547  
Shareholder Report [Line Items]  
Fund Name Cash Reserves Fund
Trading Symbol TSCXX
Annual or Semi-Annual Statement [Text Block] This semi-annual shareholder report contains important information about Cash Reserves Fund (the "fund") for the period of November 1, 2025 to April 30, 2026.
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)

Table Summary
 
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 $ 5,038,076,000
Holdings Count | Holding 207
Additional Fund Statistics [Text Block]

What are some fund statistics?

Fund Statistics

Table Summary
Total Net Assets (000s)
$5,038,076
Number of Portfolio Holdings
207
Holdings [Text Block]

Security Allocation (as a % of Net Assets)

Table Summary
Variable Rate Demand Notes
24.0%
U.S. Government Agency Repurchase Agreement
21.0
Certificate of Deposit
17.9
Financial Company Commercial Paper
15.4
Non-Financial Company Commercial Paper
9.5
Asset Backed Commercial Paper
5.4
Other Instruments
2.4
Other Asset Backed Securities
1.6
Insurance Company Funding Agreement
1.4
Short-Term and Other
1.4
Largest Holdings [Text Block]

Top Ten Holdings (as a % of Net Assets)

Table Summary
BNY Mellon
13.1%
Credit Agricole
5.9
Royal Bank of Canada
2.0
North Texas Higher Ed. Auth.
2.0
Australia & New Zealand Banking Group
2.0
BNP Paribas Securities
2.0
California PFA
2.0
Cook County
1.6
Alaska HFC, State Capital Project
1.6
Svenska Handelsbanken
1.6
Material Fund Change [Text Block]
Updated Prospectus Web Address www.troweprice.com/paperless