S000014682 [Member] Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Western Asset SMASh Series C Fund | SMASh Series C Fund | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | (2.22%) | 12.95% | (3.21%) | 1.35% | 2.93% | 15.10% | (3.22%) | 7.20% | 6.66% | 2.88% |