Label	Element	Value
Franklin Short Duration U.S. Government ETF | Collateralized Mortgage Obligations [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	39.20%
Franklin Short Duration U.S. Government ETF | U.S. Government & Agency Obligations [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	28.50%
Franklin Short Duration U.S. Government ETF | Mortgage-Backed Securities [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	24.80%
Franklin Short Duration U.S. Government ETF | Corporate Bonds & Notes [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	0.70%
Franklin Short Duration U.S. Government ETF | Short-Term Investments [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	6.80%