SUPPLEMENTAL FINANCIAL INFORMATION - Accounts Payable (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Accounts Payable [Abstract]
Accounts payable trade	$ 265	$ 277
Salaries, withholdings and payroll taxes	400	456
Ticket taxes and fees	302	242
Aircraft maintenance payable	140	65
Fuel payable	161	188
Dividends payable	107	107
Customer reimbursements and refunds	8	311
Accrued third party services	269	196
Other payable	210	162
Accounts payable	$ 1,862	$ 2,004