CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - UNAUDITED - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 19,379	$ 15,117	$ 38,630	$ 29,131
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(3,818)	(16,231)	29	(8,521)
Unrealized holding gain (loss) on short-term investments arising during period	10	68	28	(26)
Other comprehensive income (loss), net of tax	(3,808)	(16,163)	57	(8,547)
Total comprehensive income (loss), net of tax	$ 15,571	$ (1,046)	$ 38,687	$ 20,584