Revenue Recognition - Revenue by Geographic Region (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Operating revenue	$ 58,048	$ 50,582	$ 29,899
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	40,845	38,478	24,320
Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	10,458	7,429	2,537
Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	4,292	3,334	2,284
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	2,453	1,341	758
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	48,909	40,218	22,519
Passenger | Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	33,968	30,197	18,468
Passenger | Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	9,057	6,093	1,777
Passenger | Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	3,798	2,889	1,873
Passenger | Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 2,086	$ 1,039	$ 401