Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 7,460	$ 5,750	$ 8,749	$ 5,526
Other comprehensive income (loss), net of taxes:
Foreign currency translation	(1,429)	1,067	52	(1,933)
Net change in market value of investments	3	(51)	120	47
Other comprehensive income (loss)	(1,426)	1,016	172	(1,886)
Comprehensive income	$ 6,034	$ 6,766	$ 8,921	$ 3,640