Shareholder Report, Average Annual Return (Details) 74200010400_Franklin Federal Tax-Free Income Fund_Advisor Class_TSR Annual {Advisor Class} |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Apr. 30, 2026 |
Apr. 30, 2026 |
Apr. 30, 2026 |
|
| Advisor Class | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Advisor Class | ||
| Average Annual Return, Percent | 6.59% | 0.86% | 2.08% |
| Bloomberg Municipal Bond Index [Member] | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Bloomberg Municipal Bond Index | ||
| Average Annual Return, Percent | 6.34% | 0.90% | 2.20% |