Shareholder Report, Line Graph (Details) 998000_Franklin Short Duration U.S. Government 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 |
Mar. 31, 2020 |
Mar. 31, 2019 |
Mar. 31, 2018 |
Mar. 31, 2017 |
Mar. 31, 2016 |
Mar. 31, 2026 |
|
| Franklin Short Duration U.S. Government ETF | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Franklin Short Duration U.S. Government ETF (NAV) | ||||||||||
| Accumulated Value | $ 11,706 | $ 11,072 | $ 10,633 | $ 10,607 | $ 10,873 | $ 10,684 | $ 10,355 | $ 10,147 | $ 10,110 | $ 10,000 | $ 12,231 |
| Bloomberg U.S. Aggregate Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Aggregate Index | ||||||||||
| Accumulated Value | 11,342 | 10,814 | 10,633 | 11,168 | 11,651 | 11,569 | 10,620 | 10,165 | 10,044 | 10,000 | $ 11,835 |
| Bloomberg U.S. Government (1-3 Year) Index [Member] | |||||||||||
| Account Value [Line Items] | |||||||||||
| Line Graph and Table Measure Name | Bloomberg U.S. Government (1-3 Year) Index | ||||||||||
| Accumulated Value | $ 11,494 | $ 10,903 | $ 10,587 | $ 10,563 | $ 10,894 | $ 10,855 | $ 10,302 | $ 10,027 | $ 10,025 | $ 10,000 | $ 11,927 |