Revenue - Roll Forward of Frequent Flyer Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Frequent Flyer Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 7,024	$ 6,495	$ 6,675	$ 6,282
Total miles awarded	816	705	2,465	1,848
Travel miles redeemed	(740)	(601)	(1,983)	(1,489)
Non-travel miles redeemed	(24)	(21)	(81)	(63)
Total Frequent flyer deferred revenue - ending balance	$ 7,076	$ 6,578	$ 7,076	$ 6,578