INCOME TAXES - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2022	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2021
Income Tax Contingency [Line Items]
Taxes paid	$ 24
Expected additional tax payable	5
Valuation allowance	40			$ 16
Accrued tax contingencies	36	$ 21		25	$ 41
Accrued tax contingencies that would decrease effective tax rate if recognized	26
Accrued interest and penalties	4	3		$ 2
Interest and penalties expense		$ 5
Hawaiian Holdings, Inc.
Income Tax Contingency [Line Items]
Deferred income taxes	90		$ 58
Accrued tax contingencies	5
Federal
Income Tax Contingency [Line Items]
Income taxes receivable	4
Net operating loss	1,200
State
Income Tax Contingency [Line Items]
Net operating loss	$ 2,500