Shareholder Report, Line Graph (Details) 74200010400_Franklin Federal Tax-Free Income Fund_Class A1_TSR Annual {Class A1} - USD ($) |
12 Months Ended | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Apr. 30, 2025 |
Apr. 30, 2024 |
Apr. 30, 2023 |
Apr. 30, 2022 |
Apr. 30, 2021 |
Apr. 30, 2020 |
Apr. 30, 2019 |
Apr. 30, 2018 |
Apr. 30, 2017 |
Apr. 30, 2016 |
Apr. 30, 2026 |
|
| Class A1 | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Class A1 (with sales charge) | ||||||||||
| Accumulated Value | $ 10,991 | $ 10,738 | $ 10,418 | $ 10,313 | $ 11,269 | $ 10,323 | $ 10,198 | $ 9,707 | $ 9,626 | $ 9,625 | $ 11,693 |
| Bloomberg Municipal Bond Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||||||||||
| Accumulated Value | $ 11,688 | $ 11,497 | $ 11,262 | $ 10,947 | $ 11,884 | $ 11,030 | $ 10,797 | $ 10,170 | $ 10,014 | $ 10,000 | $ 12,429 |