Shareholder Report, Line Graph (Details) 1014050_Franklin Ultra Short Bond ETF_Single Class_TSR Annual {Single Class} - USD ($) |
12 Months Ended | ||||||
|---|---|---|---|---|---|---|---|
Mar. 31, 2025 |
Mar. 31, 2024 |
Mar. 31, 2023 |
Mar. 31, 2022 |
Mar. 31, 2021 |
Jul. 14, 2020 |
Mar. 31, 2026 |
|
| Franklin Ultra Short Bond ETF | |||||||
| Account Value [Line Items] | |||||||
| Line Graph and Table Measure Name | Franklin Ultra Short Bond ETF (NAV) | ||||||
| Accumulated Value | $ 11,452 | $ 10,866 | $ 10,212 | $ 10,012 | $ 10,091 | $ 10,000 | $ 11,977 |
| Bloomberg U.S. Aggregate Index [Member] | |||||||
| Account Value [Line Items] | |||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Aggregate Index | ||||||
| Accumulated Value | 9,387 | 8,950 | 8,801 | 9,243 | 9,644 | 10,000 | $ 9,795 |
| ICE BofA U.S. 3-Month Treasury Bill Index [Member] | |||||||
| Account Value [Line Items] | |||||||
| Line Graph and Table Measure Name | ICE BofA U.S. 3-Month Treasury Bill Index | ||||||
| Accumulated Value | $ 11,340 | $ 10,803 | $ 10,265 | $ 10,014 | $ 10,008 | $ 10,000 | $ 11,793 |