Revenue - Roll Forward of Frequent Flyer Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Frequent Flyer Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 6,860	$ 6,417	$ 6,675	$ 6,282
Total miles awarded	902	666	1,649	1,143
Travel miles redeemed	(712)	(566)	(1,243)	(888)
Non-travel miles redeemed	(26)	(22)	(57)	(42)
Total Frequent flyer deferred revenue - ending balance	$ 7,024	$ 6,495	$ 7,024	$ 6,495