Revenue - Air Traffic Liability Breakout (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Revenue Recognition and Deferred Revenue [Abstract]
ATL - PAX Revenue and Ancillary PAX Services	$ 2,627	$ 2,059
ATL - Loyalty Program	3,339	3,011
Air Traffic Liability Total	$ 5,966	$ 5,070	$ 5,583	$ 4,565

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