CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 11,076	$ 18,884	$ 25,943	$ 33,156
Other comprehensive income (loss), net of applicable taxes:
Foreign currency translation adjustment	2,218	(1,505)	3,030	(836)
Unrealized (loss) gain on short-term investments	0	13	(30)	6
Total other comprehensive income (loss)	2,218	(1,492)	3,000	(830)
Comprehensive income	$ 13,294	$ 17,392	$ 28,943	$ 32,326