CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Common Shares	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest
Beginning balance (in shares) at Dec. 31, 2017		128,970,776
Beginning balance at Dec. 31, 2017	$ 1,692,940	$ 872,228	$ 707,378	$ 13,417	$ 99,917
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	42,706		40,539		2,167
Dividends ($0.27 and $0.25 per share, respectively)	(32,634)		(32,634)
Issuance of shares under incentive stock plans (in shares)		204,336
Issuance of shares under incentive stock plans	5,455	$ 5,455
Stock-based compensation	1,262	$ 1,262
Repurchase of common shares (in shares)		(811)
Repurchase of common shares	(18)	$ (18)
Amortization of pension and postretirement plan liabilities	159
Actuarial change and amortization of pension and postretirement plan liabilities	159			159
Foreign currency translation adjustment	9,688			7,606	2,082
Cash flow hedges	16,615			16,381	234
Ending balance (in shares) at Mar. 31, 2018		129,174,301
Ending balance at Mar. 31, 2018	1,736,173	$ 878,927	715,283	37,563	104,400
Beginning balance (in shares) at Dec. 31, 2018		129,488,675
Beginning balance at Dec. 31, 2018	1,654,550	$ 884,263	672,371	239	97,677
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	27,793		24,794		2,999
Dividends ($0.27 and $0.25 per share, respectively)	(35,049)		(35,049)
Issuance of shares under incentive stock plans (in shares)		26,031
Issuance of shares under incentive stock plans	597	$ 597
Stock-based compensation	1,477	$ 1,477
Repurchase of common shares (in shares)		(1,140)
Repurchase of common shares	(33)	$ (33)
Amortization of pension and postretirement plan liabilities	112			112
Foreign currency translation adjustment	6,033			4,680	1,353
Cash flow hedges	(10,686)			(10,884)	198
Distribution to minority shareholder	(3,594)				(3,594)
Ending balance (in shares) at Mar. 31, 2019		129,513,566
Ending balance at Mar. 31, 2019	$ 1,641,200	$ 886,304	$ 662,116	$ (5,853)	$ 98,633