Accumulated Other Comprehensive Income (Loss) - Schedule of Components of Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	$ (4,654)	$ (3,499)	$ (4,826)	$ (1,613)
Foreign currency translation	(120)	(129)	(68)	(2,062)
Foreign currency translation before reclassification				(2,380)
Reclassification adjustment for write-off of foreign currency translation loss				318
Unrealized gain (loss) on investments, net of tax	(48)		72	47
Ending Balance	(4,822)	(3,628)	(4,822)	(3,628)
Net Unrealized Gain (Loss) on Marketable Investments [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	20	(27)	(100)	(74)
Unrealized gain (loss) on investments, net of tax	(48)		72	47
Ending Balance	(28)	(27)	(28)	(27)
Cumulative Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning Balance	(4,674)	(3,472)	(4,726)	(1,539)
Foreign currency translation	(120)	(129)	(68)
Foreign currency translation before reclassification				(2,380)
Reclassification adjustment for write-off of foreign currency translation loss				318
Ending Balance	$ (4,794)	$ (3,601)	$ (4,794)	$ (3,601)