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ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) - Schedule of AOCI Components (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | $ 10,515 | $ 10,687
Changes in fair value | (80) | (240)
Reclassification to earnings | 55 | (104)
Balance at end of period | 10,350 | 10,515
Accumulated other comprehensive income (loss) |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | 0 | 344
Balance at end of period | (25) | 0
Fuel derivatives | Fuel derivative contracts |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | (135) | 305
Changes in fair value | (130) | (312)
Reclassification to earnings | 72 | (128)
Balance at end of period | (193) | (135)
Defined benefit plan items |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | 149 | 170
Changes in fair value | 25 | (11)
Reclassification to earnings | (7) | (10)
Balance at end of period | 167 | 149
Other |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | (15) | (32)
Changes in fair value | 0 | 10
Reclassification to earnings | 8 | 7
Balance at end of period | (7) | (15)
Deferred tax impact |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | 1 | (99)
Changes in fair value | 25 | 73
Reclassification to earnings | (18) | 27
Balance at end of period | $ 8 | $ 1

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