REVENUE RECOGNITION - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Disaggregation of Revenue [Line Items]
Operating revenue	$ 12,759	$ 9,348
Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	9,396	7,549
Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	1,548	776
Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	1,280	811
Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	535	212
Passenger
Disaggregation of Revenue [Line Items]
Operating revenue	10,411	6,907
Passenger | Domestic
Disaggregation of Revenue [Line Items]
Operating revenue	7,594	5,563
Passenger | Atlantic
Disaggregation of Revenue [Line Items]
Operating revenue	1,244	539
Passenger | Latin America
Disaggregation of Revenue [Line Items]
Operating revenue	1,132	680
Passenger | Pacific
Disaggregation of Revenue [Line Items]
Operating revenue	$ 441	$ 125