Label	Element	Value
Franklin U.S. Core Bond ETF \| U.S. Government & Agency Obligations [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	36.30%
Franklin U.S. Core Bond ETF \| Corporate Bonds & Notes [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	28.60%
Franklin U.S. Core Bond ETF \| Mortgage-Backed Securities [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	25.90%
Franklin U.S. Core Bond ETF \| Collateralized Mortgage Obligations [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	5.30%
Franklin U.S. Core Bond ETF \| Municipal Bonds [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	1.40%
Franklin U.S. Core Bond ETF \| Asset-Backed Securities [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	0.70%
Franklin U.S. Core Bond ETF \| Short-Term Investments [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	1.80%