Shareholder Report, Line Graph (Details) 74200010400_Franklin Federal Tax-Free Income Fund_Advisor Class_TSR Annual {Advisor Class} - 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 |
|
| Advisor Class | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Advisor Class | ||||||||||
| Accumulated Value | $ 11,520 | $ 11,244 | $ 10,898 | $ 10,778 | $ 11,764 | $ 10,767 | $ 10,626 | $ 10,106 | $ 10,011 | $ 10,000 | $ 12,279 |
| 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 |