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Financial Derivative Instruments - Location and Amount Recognized in Income by Hedging Relationship (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Fuel derivative contracts |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of loss reclassified from AOCI into income | $ 36 |  |  |
Fuel and oil |  |  |  |
Derivative [Line Items] |  |  |  |
Total | 36 | $ 17 | $ 73 | $ 39
Fuel and oil | Cash Flow Hedging | Fuel derivative contracts |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of loss reclassified from AOCI into income | 36 | 17 | 73 | 39
Fuel and oil | Cash Flow Hedging | Other |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of loss reclassified from AOCI into income | 0 | 0 | 0 | 0
Other operating expenses |  |  |  |
Derivative [Line Items] |  |  |  |
Total | 2 | 2 | 3 | 4
Other operating expenses | Cash Flow Hedging | Fuel derivative contracts |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of loss reclassified from AOCI into income |  |  | 0 | 0
Other operating expenses | Cash Flow Hedging | Other |  |  |  |
Derivative [Line Items] |  |  |  |
Amount of loss reclassified from AOCI into income | $ 2 | $ 2 | $ 3 | $ 4

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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 4A -Subparagraph (b)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480434/815-10-50-4A + Details
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