Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 38,251	$ 40,470	$ 45,709
Other comprehensive income (loss):
Foreign currency translation adjustment	24	55	(82)
Tax benefit (provision)	(12)	(20)	11
Comprehensive income	$ 38,263	$ 40,505	$ 45,638