Unaudited Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 44,090	$ 37,333
Foreign currency translation adjustment	(570)	28
Other comprehensive income (loss), before tax	(570)	28
Income tax expense on other comprehensive income (loss)	0	0
Other comprehensive income (loss), net of tax	(570)	28
Comprehensive income	$ 43,520	$ 37,361