REVENUE FROM CONTRACTS WITH CUSTOMERS - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Deferred Revenue Arrangement [Line Items]
Receivable	$ 340		$ 296
Costs and Expenses	2,382	$ 1,883
Mileage Plan Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized	285	259
Receivable	94		$ 83
Mileage Plan Revenue [Member] | Mileage plan other revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized	(21)	(9)
Passenger Revenue [Member]
Deferred Revenue Arrangement [Line Items]
Contract liability revenue recognized	$ 485	$ 390