Shareholder Report, Average Annual Return (Details) 74200010400_Franklin Federal Tax-Free Income Fund_Class A1_TSR Annual {Class A1} |
12 Months Ended | 60 Months Ended | 120 Months Ended |
|---|---|---|---|
Apr. 30, 2026 |
Apr. 30, 2026 |
Apr. 30, 2026 |
|
| Class A1 | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Class A1 (with sales charge) | ||
| Average Annual Return, Percent | 2.40% | (0.03%) | 1.58% |
| Without Sales Load [Member] | Class A1 | |||
| Average Annual Return [Line Items] | |||
| Line Graph and Table Measure Name | Class A1 | ||
| Average Annual Return, Percent | 6.39% | 0.74% | 1.97% |
| 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% |