Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 817	$ 306
Other comprehensive (loss) income, net of taxes:
Unrealized gains on securities	0	1
Defined benefit plans:
Amortization of unrecognized amounts included in net periodic benefit costs	12	11
Foreign exchange losses	(1)	(1)
Other comprehensive income	11	11
Total comprehensive income	828	317
Total comprehensive income attributable to noncontrolling interests	(124)	(78)
Total comprehensive income (loss)	$ 704	$ 239