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, 2015	$ 663,247	$ 544	$ 54,912	$ 963,143	$ (190,486)	$ (164,866)
Net income (loss)	21,554			21,554
Other comprehensive income (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)
Previously unrecognized excess tax benefit onexercise of stock awards	317			317
Net income (loss)	7,914			7,914
Other comprehensive income (loss)	63,931				63,931
Comprehensive income (loss)	71,845
Cash dividends declared	(22,704)			(22,704)
Share-based compensation expense	6,214		6,214
Delivery of treasury shares
RSUs and PSAs	(114)		(535)			421
Employee stock options exercised — net	(456)		(1,002)			546
Ending Balance at Dec. 31, 2017	708,928	544	62,594	948,411	(140,675)	(161,946)
Reclassisfication pursuant to ASU No. 2018-02				22,298	(22,298)
Net income (loss)	(177,604)			(177,604)
Other comprehensive income (loss)	25,533				25,533
Comprehensive income (loss)	(152,071)
Tax effect on exercise of stock awards	(7)		(7)
Cash dividends declared	(22,800)			(22,800)
Share-based compensation expense	7,000		7,000
Delivery of treasury shares
RSUs and PSAs	(1,626)		(6,201)			4,575
Employee stock options exercised — net	(526)		(1,147)			621
Ending Balance at Dec. 31, 2018	$ 538,898	$ 544	$ 62,239	$ 770,305	$ (137,440)	$ (156,750)