Class K [Member] Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
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 |
|
| Class K | BlackRock Short Duration Muni Fund | Class K Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 5.20% | 2.94% | 4.53% | (2.44%) | 0.02% | 1.31% | 2.45% | 1.59% | 1.01% | (0.06%) |