v3.26.1
S000014682 [Member] Expense Example, No Redemption - Western Asset SMASh Series C Fund - SMASh Series C Fund
Feb. 28, 2026
USD ($)
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year $ 0
Expense Example, No Redemption, 3 Years 13
Expense Example, No Redemption, 5 Years 27
Expense Example, No Redemption, 10 Years $ 70