Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 44,764	$ 32,979	$ 98,860	$ 77,534
Foreign currency translation adjustments, net of tax of ($9,003), $4,779, ($13,230) and $3,010	14,689	(8,571)	21,587	(5,398)
Unrealized loss on interest rate derivatives, net of tax of $1,145, $0, $863 and $0	(1,868)		(1,408)
Comprehensive income	$ 57,585	$ 24,408	$ 119,039	$ 72,136