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Financial Derivative Instruments - Premiums for Fuel Derivative Contracts (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Fuel derivative contracts | Designated as Hedging Instrument | Fuel and oil |  |  |  |
Derivative [Line Items] |  |  |  |
Premium expense recognized in income on derivatives | $ 30 | $ 26 | $ 61 | $ 53

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- Definition The premium (cost) of a hedge, expensed during the period. + References No definition available. + Details
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