Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income (loss)	$ (2,699)	$ 3,950	$ (14,460)	$ 10,005
Other comprehensive loss, net of taxes:
Foreign currency translation	(1,614)	(602)	(1,450)	(2,293)
Net change in market value of investments		65		12
Other comprehensive loss	(1,614)	(537)	(1,450)	(2,281)
Comprehensive income (loss)	$ (4,313)	$ 3,413	$ (15,910)	$ 7,724