FAIR VALUE MEASUREMENTS - Fair Value Assets and Liabilities Measured on Recurring Basis with Unobservable Inputs (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Asset (Liability), Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other Nonoperating Income (Expense)	Other Nonoperating Income (Expense)
Fuel derivative contracts
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 223	$ 512
Included in earnings	(34)	17
Included in other comprehensive income	(130)	(312)
Purchases	123	273
Settlements	(52)	(267)
Ending Balance	130	223
The amount of total losses for the period included in other comprehensive income attributable to the change in unrealized gains or losses relating to assets still held at year-end	$ 131	$ 209