Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2017 USD ($) ReportingUnit Customer	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of reporting units | ReportingUnit	5
Foreign currency transaction losses | $	$ 2	$ 1	$ 3
Number of major customers | Customer	30
Customer Concentration Risk [Member] | Sales Revenue, Net [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue	10.00%
Customer Concentration Risk [Member] | Sales Revenue, Net [Member] | Top 30 Customers [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of revenue	33.00%