Label	Element	Value
Franklin Short-Term Municipal Income ETF | Industrial Dev. Revenue and Pollution Control [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	21.60%
Franklin Short-Term Municipal Income ETF | Housing [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	12.60%
Franklin Short-Term Municipal Income ETF | Health Care [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	12.00%
Franklin Short-Term Municipal Income ETF | Local [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	11.60%
Franklin Short-Term Municipal Income ETF | Education [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	11.20%
Franklin Short-Term Municipal Income ETF | Utilities [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	8.00%
Franklin Short-Term Municipal Income ETF | Transportation [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	7.90%
Franklin Short-Term Municipal Income ETF | Special Tax [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	5.70%
Franklin Short-Term Municipal Income ETF | Lease [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	4.80%
Franklin Short-Term Municipal Income ETF | Other Revenue Bonds [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	2.20%
Franklin Short-Term Municipal Income ETF | State General Obligation [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	2.20%
Franklin Short-Term Municipal Income ETF | Other [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	0.10%
Franklin Short-Term Municipal Income ETF | Refunded [Member]
Holdings [Line Items]	oef_HoldingsLineItems
Percent of Total Investments	oef_PctOfTotalInv	0.10%