FLEET TRANSITION (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) airline	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)
Impaired Long-Lived Assets [Line Items]
Special items - Impairment charges and other	$ 156	$ 155	$ 355	$ 376
Finance Lease, Liability	452		452
Fleet transition - impairment [Member]
Impaired Long-Lived Assets [Line Items]
Special items - Impairment charges and other	120	0	271	70
Other fleet transition costs [Member]
Impaired Long-Lived Assets [Line Items]
Special items - Impairment charges and other	$ 36	$ 155	$ 84	$ 306
A321neo [Member]
Impaired Long-Lived Assets [Line Items]
Number of Aircraft Operated | airline	10
Finance Lease, Impairment Loss	$ 123
A321neo [Member] | Aircraft purchase [Member]
Impaired Long-Lived Assets [Line Items]
Number of Aircraft Operated | airline	3
A321neo [Member] | Aircraft purchase agreement [Member]
Impaired Long-Lived Assets [Line Items]
Number of Aircraft Operated | airline	7