S000002682 [Member] Average Annual Total Returns |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| UBS Select Treasury Institutional Fund | |||
| Prospectus [Line Items] | |||
| Average Annual Return, Percent | 4.11% | 3.10% | 2.04% |