Comprehensive Loss - Differences between Net Income (Loss) and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Condensed Statement of Income Captions [Line Items]
NET LOSS	$ (231)	$ (159)
Other, net of deferred taxes of $— and $—	2	0
Total other comprehensive income (loss)	19	(147)
COMPREHENSIVE LOSS	(212)	(306)
Other deferred taxes	0	0
Fuel derivative contracts
Condensed Statement of Income Captions [Line Items]
Unrealized gain (loss) on fuel derivative instruments, net of deferred taxes of $6 and ($44)	17	(147)
Derivative deferred taxes	$ 6	$ (44)