Intangibles, Net - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite Lived Intangible Assets [Line Items]
Amortization Of Intangible Assets	$ 22	$ 21	$ 13
Minimum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of identified intangible assets	1 year
Maximum [Member]
Finite Lived Intangible Assets [Line Items]
Estimated useful lives of identified intangible assets	20 years