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	(123,155)		(123,155)
Issuance of shares under incentive stock plans (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. 2016-16 | Accounting Standards Update 2016-16 [Member]			(14,365)
Net income	35,083		33,843		1,240
Dividends	(30,753)		(30,753)
Issuance of shares under incentive stock plans (shares)		105,981
Issuance of shares under incentive stock plans	2,251	$ 2,251
Stock-based compensation	880	$ 880
Repurchase of common shares (in shares)		(298)
Repurchase of common shares	0
Actuarial change and amortization of pension and postretirement plan liabilities	116			116
Foreign currency translation adjustment	2,432			2,002	430
Cash flow hedges	2,553			2,571	(18)
Issuance of shares under equity offering, net of costs (in shares)		5,750,000
Issuance of shares under equity offering, net of costs	152,345	$ 152,345
Ending balance (in shares) at Mar. 31, 2017		128,760,051
Ending balance at Mar. 31, 2017	1,647,294	$ 865,343	$ 689,612	$ 5,545	$ 86,794
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment due to adoption of ASU No. 2016-16	$ (14,365)