Segment Information - Schedule of Net Revenues from Unaffiliated Customers by Country Based on the Location of the Customer (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 58,771	$ 56,888	$ 57,709	$ 54,462	$ 48,085	$ 53,227	$ 52,941	$ 46,027	$ 227,830	$ 200,280	$ 220,194
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									83,871	80,603	88,136
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									24,078	22,495	29,686
Asia Pacific [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									114,365	91,848	94,845
All Other Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue									$ 5,516	$ 5,334	$ 7,527