Annual Total Returns |
12 Months Ended | |||||||
|---|---|---|---|---|---|---|---|---|
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
|
| First Trust Flexible Municipal High Income ETF | First Trust Flexible Municipal High Income ETF | ||||||||
| Prospectus [Line Items] | ||||||||
| Annual Return [Percent] | 4.65% | 7.99% | (19.52%) | 8.28% | 7.06% | 16.63% | (4.28%) | 6.24% |