Revenue - Air Traffic Liability Breakout (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Dec. 31, 2018
Revenue Recognition and Deferred Revenue [Abstract]
ATL - PAX Revenue and Ancillary PAX Services	$ 2,907	$ 2,125
AirTrafficLiabilityLoyaltyProgram	4,187	3,385
AirTrafficLiabilityTotal	$ 7,094	$ 5,510	$ 5,966	$ 5,070

Air Traffic Liability Passenger Revenue and Ancillary Passenger Services

No definition available.

Name:	luv_AirTrafficLiabilityPassengerRevenueandAncillaryPassengerServices
Namespace Prefix:	luv_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant