REVENUE FROM CONTRACTS WITH CUSTOMERS Contract Liabilities Activity (Details) - Mileage Plan Revenue [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Contract with Customer, Liability	$ 2,497	$ 2,358	$ 2,277
Contract with Customer, Liability, Increase From Issuance of Credits	1,082	763
Mileage Plan Services, Other [Member]
Contract with Customer, Liability, Revenue Recognized	(65)	(43)
Passenger Services [Member]
Contract with Customer, Liability, Revenue Recognized	$ (878)	$ (639)