Other Income (Expense), Net - Schedule of Other Income (Expense), Net (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Other Income and Expenses [Abstract]
Interest and amortization expense	$ (597)	$ (600)	$ (1,799)	$ (1,910)
Foreign exchange loss	(163)	(4)	(565)	(14)
Investment income	619	144	1,293	434
Other income (expense), net	$ (141)	$ (460)	$ (1,071)	$ (1,490)