Consolidated Statement of Comprehensive Income (Loss) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Net income (loss)	$ 465	$ 539	$ 977
Unrealized gain (loss) on defined benefit plan items, net of deferred taxes of ($5), $24, and $25	(16)	80	84
Other, net of deferred taxes of $4, $—, and ($13)	(4)	0	(47)
OTHER COMPREHENSIVE INCOME (LOSS)	(344)	(44)	513
COMPREHENSIVE INCOME	121	495	1,490
Fuel derivative contracts
Unrealized gain (loss) on derivatives, net of tax	(337)	(143)	469
Interest rate derivatives
Unrealized gain (loss) on derivatives, net of tax	$ 13	$ 19	$ 7