FLEET TRANSITION (Details) $ in Millions	1 Months Ended	3 Months Ended
	Apr. 30, 2023 USD ($) airline	Mar. 31, 2023 USD ($) airline	Mar. 31, 2022 USD ($)
Impaired Long-Lived Assets [Line Items]
Asset Impairment Charges		$ 13	$ 75
Impairment Charges
Impaired Long-Lived Assets [Line Items]
Asset Impairment Charges		0	70
Accelerated aircraft ownership expenses [Member]
Impaired Long-Lived Assets [Line Items]
Asset Impairment Charges		6	0
Lease return costs and other expenses
Impaired Long-Lived Assets [Line Items]
Asset Impairment Charges		$ 7	$ 5
A321neo [Member]
Impaired Long-Lived Assets [Line Items]
Number of Aircraft Operated | airline		10
A321neo [Member] | Subsequent Event [Member]
Impaired Long-Lived Assets [Line Items]
Number of Aircraft Operated | airline	4
Remainder of 2023	$ 250