Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]	Treasury Stock [Member]
Beginning Balance at Dec. 31, 2013	$ 684,476	$ 544	$ 53,940	$ 869,329	$ (75,357)	$ (163,980)
Net income	69,246			69,246
Other comprehensive loss	(79,513)				(79,513)
Comprehensive income (loss)	(10,267)
Tax effect on exercise of stock awards	(14)		(14)
Cash dividends declared	(19,107)			(19,107)
Share-based compensation expense	4,738		4,738
Repurchase of common shares	(12,180)					(12,180)
Delivery of treasury shares
RSUs and PSAs	(1,758)		(4,121)			2,363
401 (k) plans	3,093		1,318			1,775
Employee stock options exercised — net	128		(1,519)			1,647
Ending Balance at Dec. 31, 2014	649,109	544	54,342	919,468	(154,870)	(170,375)
Net income	64,575			64,575
Other comprehensive loss	(35,616)				(35,616)
Comprehensive income (loss)	28,959
Tax effect on exercise of stock awards	843		843
Cash dividends declared	(20,900)			(20,900)
Share-based compensation expense	4,403		4,403
Delivery of treasury shares
RSUs and PSAs	(1,976)		(5,078)			3,102
401 (k) plans	2,848		838			2,010
Employee stock options exercised — net	(39)		(436)			397
Ending Balance at Dec. 31, 2015	663,247	544	54,912	963,143	(190,486)	(164,866)
Net income	21,554			21,554
Other comprehensive loss	(14,120)				(14,120)
Comprehensive income (loss)	7,434
Tax effect on exercise of stock awards	58		58
Cash dividends declared	(21,813)			(21,813)
Share-based compensation expense	5,889		5,889
Delivery of treasury shares
RSUs and PSAs	(751)		(2,375)			1,624
Employee stock options exercised — net	(238)		(567)			329
Ending Balance at Dec. 31, 2016	$ 653,826	$ 544	$ 57,917	$ 962,884	$ (204,606)	$ (162,913)