Consolidated Statements Of Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income	Non- controlling Interest
Balance, beginning of year (in shares) at Dec. 31, 2017		53,629,439	378,269
Balance, beginning of period at Dec. 31, 2017	$ 2,022,322	$ 5	$ (48,933)	$ 704,727	$ 1,443,867	$ (77,344)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		196,308
Exercise of stock options and vesting of RSU's and PSU's	3,113			3,113
Purchased common stock (in shares)		(82,898)	(82,898)
Purchased common stock	(20,071)		$ (20,071)
Stock-based compensation	6,415			6,415
Net income	106,334				106,334
Foreign currency translation adjustments	26,638					26,638
Unrealized (loss) gain on derivatives	2					2
Balance, end of period (in shares) at Mar. 31, 2018		53,742,849	461,167
Balance, end of period at Mar. 31, 2018	2,145,369	$ 5	$ (69,004)	714,255	1,550,807	(50,694)	0
Balance, beginning of year (in shares) at Dec. 31, 2018		52,941,607	1,430,094
Balance, beginning of period at Dec. 31, 2018	2,206,235	$ 5	$ (224,998)	744,937	1,848,500	(162,896)	687
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options and vesting of RSU's and PSU's (in shares)		166,606
Exercise of stock options and vesting of RSU's and PSU's	(6,149)			(6,149)
Stock-based compensation	8,138			8,138
Net income	54,916				55,159		(243)
Foreign currency translation adjustments	5,161					5,158	3
Unrealized (loss) gain on derivatives	(13)					(13)
Balance, end of period (in shares) at Mar. 31, 2019		53,108,213	1,430,094
Balance, end of period at Mar. 31, 2019	$ 2,268,288	$ 5	$ (224,998)	$ 746,926	$ 1,903,659	$ (157,751)	$ 447