Revenue - Air Traffic Liability Breakout (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Air traffic liability - passenger travel and ancillary passenger services	$ 3,726	$ 2,936
Air traffic liability - loyalty program	4,884	4,789	$ 4,623	$ 4,447
Total Air traffic liability	$ 8,610	$ 7,725	$ 7,732	$ 7,133