Financial Derivative Instruments and Risk Management - Effect of Fuel and Interest Rate Derivative Instruments (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Interest Rate Swap
Derivative [Line Items]
Amortization of cash flow hedge gains (losses), net of tax	$ (1)	$ (1)	$ (1)

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.

Reference 1: 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

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