Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 25,086	$ 24,269
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	215	215
Foreign currency translation adjustment	855	568
Other comprehensive income, net of tax	1,070	783
Comprehensive income	$ 26,156	$ 25,052