FINANCIAL DERIVATIVE INSTRUMENTS - Premium Expense (Benefit) for Fuel Derivative Contracts (Details) - Fuel derivative contracts - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Designated as Hedging Instrument \| Fuel and oil
Derivative [Line Items]
Premium expense (benefit) recognized in income on derivatives	$ 148	$ 121	$ 105
Not Designated as Hedging Instrument, Economic Hedge \| Other (gains) losses, net
Derivative [Line Items]
Premium expense (benefit) recognized in income on derivatives	$ 9	$ 0	$ (28)

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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