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Financial Derivative Instruments - Premium Expense (Benefit) for Fuel Derivative Contracts (Details) - Fuel derivative contracts - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Designated as Hedging Instrument | Fuel and oil |  |  |  |
Derivative [Line Items] |  |  |  |
Expense (benefit) recognized in income on derivatives | $ 36 | $ 40 | $ 73 | $ 79
Not Designated as Hedging Instrument | Other (gains) losses, net |  |  |  |
Derivative [Line Items] |  |  |  |
Premium expense recognized in income on derivatives | $ 0 | $ (1) | $ 0 | $ (1)

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- Definition Derivative, Premium (Benefit) Expense + References No definition available. + Details
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- Definition The premium (cost) of a hedge, expensed during the period. + References No definition available. + Details
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 815 -SubTopic 20 -Name Accounting Standards Codification -Section 25 -Paragraph 6A -Publisher FASB -URI https://asc.fasb.org/1943274/2147480682/815-20-25-6A Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 815 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480237/815-40-50-5 + Details
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