Accumulated Other Comprehensive Income (Loss) - Schedule of Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (7,573)	$ (4,826)
Foreign currency translation	790	1,481
Unrealized gain on investments, net of tax	17	117
Ending Balance	(6,766)	(3,228)
Net Unrealized Gain (Loss) on Marketable Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(83)	(100)
Unrealized gain on investments, net of tax	17	117
Ending Balance	(66)	17
Cumulative Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(7,490)	(4,726)
Foreign currency translation	790	1,481
Ending Balance	$ (6,700)	$ (3,245)