Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Shares	Retained Earnings	Accumulated Other Comprehensive Income/(Loss)	Non-controlling Interest
Beginning balance (in shares) at Dec. 31, 2015		122,770,217
Beginning balance at Dec. 31, 2015	$ 1,361,740	$ 708,827	$ 612,760	$ (33,503)	$ 73,656
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	217,770		211,972		5,798
Dividends ($1.00, $1.00, and $1.06 per share, respectively)	(123,155)		(123,155)
Issuance of shares under incentive stock plans, (in shares)		179,743
Issuance of shares under incentive stock plans	1,576	$ 1,576
Stock-based compensation	5,136	$ 5,136
Repurchase of common shares, (in shares)		(45,592)
Repurchase of common shares	(868)	$ (178)	(690)
Actuarial change and amortization of pension and postretirement plan liabilities	5,533			5,533
Foreign currency translation adjustment	6,322			2,780	3,542
Cash flow hedges	22,822			22,608	214
Recapitalization of New Zealand Joint Venture	0	(5,398)		3,438	1,960
Recapitalization costs	(124)	$ (96)			(28)
Ending balance (in shares) at Dec. 31, 2016		122,904,368
Ending balance at Dec. 31, 2016	1,496,752	$ 709,867	700,887	856	85,142
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment due to adoption of ASU No. 2018-02 | Accounting Standards Update 2016-16	(14,365)		(14,365)
Net income	161,579		148,842		12,737
Dividends ($1.00, $1.00, and $1.06 per share, respectively)	(127,986)		(127,986)
Issuance of shares under incentive stock plans, (in shares)		322,314
Issuance of shares under incentive stock plans	4,751	$ 4,751
Stock-based compensation	5,396	$ 5,396
Repurchase of common shares, (in shares)		(5,906)
Repurchase of common shares	(176)	$ (176)
Actuarial change and amortization of pension and postretirement plan liabilities	(208)			(208)
Foreign currency translation adjustment	9,114			7,416	1,698
Cash flow hedges	5,693			5,353	340
Issuance of shares under equity offering, net of costs (in shares)		5,750,000
Issuance of shares under equity offering, net of costs	152,390	$ 152,390
Ending balance (in shares) at Dec. 31, 2017		128,970,776
Ending balance at Dec. 31, 2017	1,692,940	$ 872,228	707,378	13,417	99,917
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment due to adoption of ASU No. 2018-02 | Accounting Standards Update 2018-02	0		711	(711)
Net income	117,330		102,216		15,114
Dividends ($1.00, $1.00, and $1.06 per share, respectively)	(137,934)		(137,934)
Issuance of shares under incentive stock plans, (in shares)		599,422
Issuance of shares under incentive stock plans	8,591	$ 8,591
Stock-based compensation	6,428	$ 6,428
Repurchase of common shares, (in shares)		(81,523)
Repurchase of common shares	(2,984)	$ (2,984)
Actuarial change and amortization of pension and postretirement plan liabilities	(919)			(919)
Foreign currency translation adjustment	(22,759)			(17,329)	(5,430)
Cash flow hedges	5,029			5,781	(752)
Distribution to minority shareholder	(11,172)				(11,172)
Ending balance (in shares) at Dec. 31, 2018		129,488,675
Ending balance at Dec. 31, 2018	$ 1,654,550	$ 884,263	$ 672,371	$ 239	$ 97,677