Revenue - Roll Forward of Frequent Flyer Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Frequent Flyer Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 6,417	$ 6,109	$ 6,282	$ 5,975
Total miles awarded	666	360	1,143	632
Travel miles redeemed	(566)	(267)	(888)	(390)
Non-travel miles redeemed	(22)	(17)	(42)	(32)
Total Frequent flyer deferred revenue - ending balance	$ 6,495	$ 6,185	$ 6,495	$ 6,185