Property, Plant and Equipment, net - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 238	$ 236
Less: accumulated depreciation	(119)	(93)
Property, plant and equipment, net	119	143	$ 165
Information Technology Assets [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	48	47
Operating Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	93	93
Buildings and Land [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 97	95
Construction in progress [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross		$ 1
Minimum [Member] | Information Technology Assets [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	1 year
Minimum [Member] | Operating Equipment [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	2 years
Minimum [Member] | Buildings [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	5 years
Maximum [Member] | Information Technology Assets [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	7 years
Maximum [Member] | Operating Equipment [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	15 years
Maximum [Member] | Buildings [Member]
Property Plant And Equipment [Line Items]
Property plant and equipment estimated useful lives	35 years