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 National Municipal Fund | Class K Shares | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 3.30% | 1.92% | 6.29% | (10.17%) | 2.34% | 4.22% | 7.43% | 0.66% | 5.46% | 0.51% |