Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (234)	$ 664	$ (232)	$ 2,516
Defined benefit plans:
Amortization of unrecognized amounts included in net periodic benefit costs	11	13	35	36
Foreign exchange losses	0	(1)	0	(2)
Other comprehensive income	11	12	35	34
Total comprehensive (loss) income	(223)	676	(197)	2,550
Total comprehensive loss (income) attributable to noncontrolling interests	28	(109)	(16)	(399)
Total comprehensive income (loss)	$ (195)	$ 567	$ (213)	$ 2,151