Income Taxes - Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal	$ 10	$ 14	$ 84
State	8	6	4
Foreign	62	31	32
Total current	80	51	120
Deferred:
Federal	20	(31)	(117)
State	(10)	(6)	(24)
Foreign	(19)	(6)	(1)
Total deferred	(9)	(43)	(142)
(Benefit) provision for income taxes	$ 71	$ 8	$ (22)