Property, Plant and Equipment, net - Summary of Property, Plant and Equipment (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	$ 232	$ 238
Less: accumulated depreciation	(127)	(119)
Property, plant and equipment, net	105	119
Information Technology Assets [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	45	48
Operating Equipment [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	90	93
Buildings and Land [Member]
Property Plant And Equipment [Line Items]
Property, plant and equipment, gross	96	$ 97
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