REVENUE RECOGNITION - Passenger Revenue (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Operating revenue	$ 50,582	$ 29,899	$ 17,095
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	40,218	22,519	12,883
Ticket
Disaggregation of Revenue [Line Items]
Operating revenue	35,626	19,339	10,970
Loyalty travel awards
Disaggregation of Revenue [Line Items]
Operating revenue	2,898	1,786	935
Travel-related services
Disaggregation of Revenue [Line Items]
Operating revenue	$ 1,694	$ 1,394	$ 978