COMMITMENTS AND CONTINGENCIES - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2025 USD ($) aircraft
Loss Contingencies [Line Items]
Line of credit facility, asset restrictions, unrestricted cash and marketable securities | $	$ 500
Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	189
Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	71
Virgin Group trademark license agreement
Loss Contingencies [Line Items]
Damages sought | $	$ 8
Damages awarded | $	32
Payment accrual | $	$ 36
B737-10 | Boeing | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	53
B737-10 | Boeing | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	35
Purchase agreement, quantity exercised	52
B787 | Firm Orders
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	12
B787 | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity required	0
B787 | Boeing | Options and Other Rights
Unrecorded Unconditional Purchase Obligation [Line Items]
Purchase agreement, quantity exercised	5