Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Capital in Excess of Par Value	Retained Deficit	Accumulated Other Comprehensive Loss
Balance, value at Dec. 31, 2014	$ 77,454	$ 218	$ (1,060)	$ 331,391	$ (114,648)	$ (138,447)
Balance, shares at Dec. 31, 2014		21,843,851	34,985
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	66,333				66,333
Other comprehensive income (loss)	18,215					18,215
Income tax effect from share-based compensation arrangements	2,797			2,797
Stock compensation expense	5,873			5,873
Stock issued, value	(3,378)		$ (11,887)	(8,509)
Stock issued, shares			336,741
Stock withheld for employee taxes	(796)			(796)
Dividends	(9,597)				(9,597)
Purchase of treasury shares, value	(15,275)		$ (15,275)
Purchase of treasury shares, shares			412,473
Balance value at Dec. 31, 2015	148,382	$ 218	$ (4,448)	330,756	(57,912)	(120,232)
Balance, shares at Dec. 31, 2015		21,843,851	110,717
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	10,073				10,073
Other comprehensive income (loss)	(4,965)					(4,965)
Income tax effect from share-based compensation arrangements	(534)			(534)
Stock compensation expense	3,724			3,724
Stock issued, value	(1,404)	$ (1)	$ (6,448)	(3,329)	(1,716)
Stock issued, shares		20,690	222,009
Stock withheld for employee taxes	(895)			(895)
Dividends	(10,070)				(10,070)
Purchase of treasury shares, value	(2,000)		$ (2,000)
Purchase of treasury shares, shares			111,292
Balance value at Dec. 31, 2016	145,119	$ 219	$ 0	329,722	(59,625)	(125,197)
Balance, shares at Dec. 31, 2016		21,864,541	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative-effect adjustment for the adoption of ASU 2016-09	2,310			127	2,183
Net income (loss)	(93,368)				(93,368)
Other comprehensive income (loss)	20,025					20,025
Stock compensation expense	3,372			3,372
Stock issued, value	(418)	$ (1)		(417)
Stock issued, shares		153,469
Stock withheld for employee taxes	(627)			(627)
Dividends	(10,355)				(10,355)
Purchase of treasury shares, shares			0
Balance value at Dec. 31, 2017	$ 66,894	$ 220	$ 0	$ 333,011	$ (161,165)	$ (105,172)
Balance, shares at Dec. 31, 2017		22,018,010	0