Revenue - Air Traffic Liability - Loyalty Program Rollforward (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Change in Contract With Customer, Liability [Roll Forward]
Beginning balance	$ 4,916	$ 5,189
Amounts deferred associated with points awarded	893	846
Ending balance	4,987	5,190
Passenger Customer
Change in Contract With Customer, Liability [Roll Forward]
Revenue recognized from points redeemed	(799)	(825)
Other
Change in Contract With Customer, Liability [Roll Forward]
Revenue recognized from points redeemed	$ (23)	$ (20)