Investor A C and Institutional [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 |
|
| Investor A, C and Institutional | BlackRock Strategic Municipal Opportunities Fund | Institutional Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 3.26% | 5.17% | (11.53%) | 5.83% | 0.57% | 6.66% | 1.26% | 8.05% | 0.79% | 3.56% |