Shareholder Report, Line Graph (Details) - USD ($) |
6 Months Ended | 12 Months Ended | 18 Months Ended | 24 Months Ended | 30 Months Ended | 36 Months Ended | 42 Months Ended | 48 Months Ended | 54 Months Ended | 60 Months Ended | 66 Months Ended | 72 Months Ended | 78 Months Ended | 84 Months Ended | 90 Months Ended | 96 Months Ended | 102 Months Ended | 108 Months Ended | 114 Months Ended | 120 Months Ended | |||
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Jan. 27, 2017 |
Jul. 31, 2016 |
Jul. 31, 2017 |
Jul. 31, 2026 |
Jul. 31, 2017 |
Jul. 31, 2018 |
Jul. 31, 2018 |
Jul. 31, 2019 |
Jul. 31, 2019 |
Jul. 31, 2020 |
Jul. 31, 2020 |
Jul. 31, 2021 |
Jul. 31, 2021 |
Jul. 31, 2022 |
Jul. 31, 2022 |
Jul. 31, 2023 |
Jul. 31, 2023 |
Jul. 31, 2024 |
Jul. 31, 2024 |
Jul. 31, 2025 |
Jul. 31, 2025 |
Jul. 31, 2026 |
Jul. 31, 2026 |
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| American High-Income Municipal Bond Fund® - Class A | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class A (with sales charge) | ||||||||||||||||||||||
| Accumulated Value | $ 9,625 | $ 9,698 | $ 10,091 | $ 10,826 | $ 11,116 | $ 12,174 | $ 11,226 | $ 11,171 | $ 12,151 | $ 12,163 | $ 13,021 | ||||||||||||
| American High-Income Municipal Bond Fund® - Class C | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class C (with sales charge) | ||||||||||||||||||||||
| Accumulated Value | 10,000 | 10,000 | 10,329 | 11,000 | 11,216 | 12,199 | 11,170 | 11,036 | 11,916 | 11,927 | 12,768 | ||||||||||||
| American High-Income Municipal Bond Fund® - Class F-1 | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class F-1 | ||||||||||||||||||||||
| Accumulated Value | 10,000 | 10,068 | 10,470 | 11,225 | 11,523 | 12,617 | 11,631 | 11,571 | 12,581 | 12,591 | 13,476 | ||||||||||||
| American High-Income Municipal Bond Fund® - Class F-2 | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class F-2 | ||||||||||||||||||||||
| Accumulated Value | 10,000 | 10,093 | 10,523 | 11,312 | 11,643 | 12,782 | 11,815 | 11,784 | 12,847 | 12,891 | 13,833 | ||||||||||||
| American High-Income Municipal Bond Fund® - Class F-3 | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class F-3 | ||||||||||||||||||||||
| Accumulated Value | $ 10,000 | $ 10,496 | $ 10,955 | $ 11,788 | $ 12,146 | $ 13,347 | $ 12,350 | $ 12,331 | $ 13,459 | $ 13,519 | $ 14,524 | ||||||||||||
| American High-Income Municipal Bond Fund® - Class R-6 | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | American High-Income Municipal Bond Fund — Class R-6 | ||||||||||||||||||||||
| Accumulated Value | 10,000 | 10,105 | 10,547 | 11,350 | 11,695 | 12,852 | 11,892 | 11,874 | 12,959 | 13,018 | 13,983 | ||||||||||||
| Bloomberg Municipal Bond Index [Member] | |||||||||||||||||||||||
| Account Value [Line Items] | |||||||||||||||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||||||||||||||
| Accumulated Value | $ 10,000 | $ 10,000 | $ 10,391 | $ 10,026 | $ 10,494 | $ 10,125 | $ 11,261 | $ 10,865 | $ 11,865 | $ 11,447 | $ 12,255 | $ 11,824 | $ 11,406 | $ 11,005 | $ 11,512 | $ 11,107 | $ 11,943 | $ 11,523 | $ 11,942 | $ 11,522 | $ 12,571 | $ 12,129 | |