v3.26.1
S000052306 [Member] Average Annual Total Returns - UBS Prime Reserves Fund
12 Months Ended 60 Months Ended 119 Months Ended
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Prospectus [Line Items]      
Average Annual Return, Percent 4.23% 3.21% 2.21%
Performance Inception Date     Jan. 19, 2016