Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 124	$ (74)	$ (425)	$ 2
Defined benefit plans:
Amortization of unrecognized amounts included in net periodic benefit costs	12	13	24	24
Foreign exchange gains (losses)	4	0	(1)	0
Other comprehensive income	16	13	23	24
Total comprehensive income (loss)	140	(61)	(402)	26
Total comprehensive (income) loss attributable to noncontrolling interests	(71)	1	(12)	(44)
Total comprehensive income (loss)	$ 69	$ (60)	$ (414)	$ (18)