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Comprehensive Income - Schedule of AOCI Components (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | $ 8,000 | $ 10,350
Deferred tax impact, beginning balance | 11 | 8
Changes in fair value | 0 | (69)
Changes in fair value, deferred tax impact | 0 | 21
Reclassification to earnings | 29 | 88
Reclassification to earnings, deferred tax impact | (9) | (27)
Balance at end of period | 7,776 | 7,776
Deferred tax impact, ending balance | 2 | 2
Accumulated other comprehensive income (loss) |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | (35) | (25)
Balance at end of period | (6) | (6)
Fuel derivatives |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | (209) | (193)
Changes in fair value | 0 | (90)
Reclassification to earnings | 36 | 110
Balance at end of period | (173) | (173)
Defined benefit plan items |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | 167 | 167
Changes in fair value | 0 | 0
Reclassification to earnings | 0 | 0
Balance at end of period | 167 | 167
Other |  |
AOCI Attributable to Parent, Net of Tax [Roll Forward] |  |
Balance at beginning of period | (4) | (7)
Changes in fair value | 0 | 0
Reclassification to earnings | 2 | 5
Balance at end of period | $ (2) | $ (2)

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