Income Taxes - Schedule of Composition of Net Deferred Tax Balances (Detail) - USD ($) $ in Millions		Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Deferred income tax assets	[1]	$ 6	$ 4
Deferred income tax liabilities		(65)	(2,437)
Net deferred tax liability		$ (59)	$ (2,433)

[1] Included within Other assets in our consolidated balance sheets.