Revenue - Air Traffic Liability Breakout (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
ATL - PAX Revenue and Ancillary PAX Services	$ 2,686	$ 2,125
ATL - Loyalty Program	4,447	3,385
Air Traffic Liability Total	$ 7,133	$ 5,510	$ 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