CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - UNAUDITED - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 13,566	$ 21,559	$ 45,446	$ 60,189
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	7,667	(6,897)	(4,746)	(6,868)
Unrealized holding gains (losses) on short-term investments arising during period	(14)	(4)	14	24
Other comprehensive income (loss), net of tax	7,653	(6,901)	(4,732)	(6,844)
Total comprehensive income, net of tax	$ 21,219	$ 14,658	$ 40,714	$ 53,345