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

Name:	us-gaap_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

FINANCIAL DERIVATIVE INSTRUMENTS - Premiums for Fuel Derivative Contracts (Details) - Fuel derivative contracts - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Designated as Hedging Instrument \| Fuel and oil
Derivative [Line Items]
Premium (benefit) expense recognized in income on derivatives			$ 121	$ 105	$ 57
Not Designated as Hedging Instrument, Economic Hedge \| Other (gains)/losses, net
Derivative [Line Items]
Premium (benefit) expense recognized in income on derivatives	$ 0	$ (28)			$ 43