Segment And Geographic Information - Schedule of Geographic Revenue Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 67,255	$ 59,977
Percentage of revenue	100.00%	100.00%
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 33,405	$ 28,661
Percentage of revenue	50.00%	48.00%
Korea
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 6,887	$ 13,821
Percentage of revenue	10.00%	23.00%
Taiwan
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 7,991	$ 7,199
Percentage of revenue	12.00%	12.00%
Japan
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 13,891	$ 3,677
Percentage of revenue	21.00%	6.00%
Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Foreign revenues	$ 5,081	$ 6,619
Percentage of revenue	7.00%	11.00%