LONG-TERM DEBT - LINE OF CREDIT (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Jun. 30, 2022 USD ($) airline	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Line of Credit Facility [Line Items]
Proceeds from Issuance of Secured Debt			$ 0	$ 363
Adjustments to Additional Paid in Capital, Warrant Issued	$ 8	$ 8
Line of Credit Facility, Number of Credit Facilities | airline			3
Line of Credit Facility, Maximum Borrowing Capacity			$ 486
Line of Credit Facility, Asset Restrictions			500
Credit Facility 1 [Member] | Secured by certain accounts receivable, spare engines, spare parts and ground service equipment [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			150
Credit Facility 2 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			250
Credit Facility 3 [Member] | Secured by aircraft [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity			$ 86
US Treasury CARES Act Loan [Member]
Line of Credit Facility [Line Items]
Adjustments to Additional Paid in Capital, Warrant Issued					$ 30