Comprehensive Income (Loss) - Differences between Net Income and Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Condensed Statement of Income Captions [Line Items]
NET INCOME	$ 277			$ 446			$ 759	$ 909
Other, net of deferred taxes of $— and $—							0	(47)
Total other comprehensive income (loss)	(500)			131			(83)	391
COMPREHENSIVE INCOME (LOSS)	(223)	$ 674	$ 225	577	$ 544	$ 180	676	1,300
Other deferred taxes							0	(13)
Fuel derivative contracts
Condensed Statement of Income Captions [Line Items]
Unrealized gain (loss) on derivative instruments, net of deferred taxes	(504)			129			(101)	430
Derivative deferred taxes	(153)			39			(31)	131
Interest rate derivatives
Condensed Statement of Income Captions [Line Items]
Unrealized gain (loss) on derivative instruments, net of deferred taxes	4			2			18	8
Derivative deferred taxes	$ 0			$ 1			$ 5	$ 2