FLEET TRANSITION (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	$ 392	$ 496	$ (1)
Finance leased asset, Number of units | aircraft	1
Fleet transition - impairment
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	$ 268	70
Other fleet transition costs
Impaired Long-Lived Assets Held and Used [Line Items]
Special Items - Impairment charges and other | $	124	$ 426
A321neo [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Finance Lease, Impairment Loss | $	$ 278
Number of Aircraft Operated | aircraft	10
A321neo [Member] | Other Current Assets [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Number of Aircraft Operated | aircraft	2
A321neo [Member] | Accounts Receivable [Member]
Impaired Long-Lived Assets Held and Used [Line Items]
Number of Aircraft Operated | aircraft	2