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Financial Derivative Instruments - Premiums for Fuel Derivative Contracts (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Fuel derivative contracts | Designated as Hedging Instrument | Fuel and oil |  |
Derivative [Line Items] |  |
Premium expense recognized in income on derivatives | $ 37 | $ 39

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