INCOME TAXES - Deferred taxes (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets:
Net Operating Loss	$ 77,920	$ 75,389
Operating Lease Obligations	16,544	32,942
Finance Lease Obligations	40,178	20,095
Goodwill and Other Intangible Assets	9,699	12,586
Loyalty Program Liabilities	4,407	4,911
Accrued Maintenance	718	4,434
Other	5,105	4,318
Total Deferred Tax Assets	154,571	154,675
Deferred Tax Liabilities:
Accelerated Depreciation	(80,001)	(67,105)
Operating Lease Right-of-use Assets	(14,181)	(27,892)
Finance Lease Assets	(41,652)	(23,462)
Total Deferred Tax Liabilities	(135,834)	(118,459)
Total Net Deferred Tax Assets	$ 18,737	$ 36,216