Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 15,380	$ 15,140	$ 17,651
Other comprehensive income (loss), net of taxes:
Foreign currency translation	(3,257)	5,593	(2,764)
Net change in market value of investments	141	(32)	17
Other comprehensive income (loss)	(3,116)	5,561	(2,747)
Comprehensive income	$ 12,264	$ 20,701	$ 14,904