Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 47,535	$ 49,484	$ 125,069	$ 179,565
Foreign currency translation adjustments, net of tax of $586, $4,404, $3,596 and $16,666	(1,050)	(7,718)	(6,448)	(29,436)
Unrealized loss on interest rate derivatives, net of tax of $412, $0, $412 and $0	(671)	0	(671)	0
Comprehensive income	$ 45,814	$ 41,766	$ 117,950	$ 150,129