GENERAL AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - LEASE RETURN PROVISION (Details) - USD ($) $ in Millions	Dec. 31, 2025	Dec. 31, 2024
Lease Return Provision [Line Items]
Leased aircraft liability	$ (72)	$ (74)
Current Accrued Liabilities
Lease Return Provision [Line Items]
Leased aircraft liability	(5)	(20)
Other Noncurrent Liabilities
Lease Return Provision [Line Items]
Leased aircraft liability	$ (67)	$ (54)