Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 13,616	$ 13,746	$ 28,952	$ 31,822
Other comprehensive income (loss):
Foreign currency translation adjustment	(31)	(48)	58	(25)
Tax benefit (provision)	7	8	(23)	4
Comprehensive income	$ 13,592	$ 13,706	$ 28,987	$ 31,801