CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ (130)	$ 359	$ (331)	$ (529)
Net income attributable to noncontrolling interest			1	1
Net income (loss) attributable to controlling interest	(130)	359	(332)	(530)
Components of net periodic benefit costs before reclassifications			(5)	(9)
Components of net periodic benefit costs reclassified to net income (loss)	3	2	7	6
Other comprehensive income (loss) before income taxes	3	2	2	(3)
Other comprehensive income (loss)	3	2	2	(3)
Other comprehensive income (loss) attributable to controlling interest	3	2	2	(3)
Total comprehensive income (loss)	(127)	361	(329)	(532)
Total comprehensive income attributable to noncontrolling interest			1	1
Total comprehensive income (loss) attributable to controlling interest	$ (127)	$ 361	$ (330)	$ (533)