Revenue - Roll Forward of Frequent Flyer Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Frequent Flyer Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 7,143	$ 6,675
Total miles awarded	840	747
Travel miles redeemed	(665)	(531)
Non-travel miles redeemed	(39)	(31)
Total Frequent flyer deferred revenue - ending balance	$ 7,279	$ 6,860