Significant Accounting Policies - Roll Forward of Frequent Flier Deferred Revenue (Details) - Frequent Flyer - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Movement in Deferred Revenue [Roll Forward]
Total Frequent flyer deferred revenue - beginning balance	$ 6,282	$ 5,975
Total miles awarded	2,558	1,545
Travel miles redeemed	(2,079)	(1,171)
Non-travel miles redeemed	(86)	(67)
Total Frequent flyer deferred revenue - ending balance	$ 6,675	$ 6,282