Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 47,595	$ 47,565	$ 121,334	$ 107,550
Other comprehensive income, net of tax:
Amortization of loss on cash flow hedge	215	215	646	646
Foreign currency translation adjustment	851	137	2,842	1,036
Other comprehensive income, net of tax	1,066	352	3,488	1,682
Comprehensive income	$ 48,661	$ 47,917	$ 124,822	$ 109,232