Investor A1 [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 A1 | BlackRock Strategic Municipal Opportunities Fund | Investor A1 Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 3.20% | 5.10% | (11.59%) | 5.76% | 0.57% | 6.50% | 1.19% | 7.97% | 0.72% | 3.56% |