Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 76	$ 817
Defined benefit plans:
Amortization of unrecognized amounts included in net periodic benefit costs	11	12
Foreign exchange losses	0	(1)
Other comprehensive income	11	11
Total comprehensive income	87	828
Total comprehensive income attributable to noncontrolling interests	(45)	(124)
Total comprehensive income (loss)	$ 42	$ 704