Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Capital in Excess of Par Value [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Stock Trusts [Member]	Accumulated Other Comprehensive Income (loss) [Member]
Balance at Dec. 31, 2014	$ 110,966	$ 270	$ 125,884	$ 118,999	$ (63,511)	$ (55,083)	$ (15,593)
Balance, shares at Dec. 31, 2014		27,018,000			8,486,000	3,363,000
Employee Stock Purchase Plan share issuance	276		(5)		$ 281
Employee Stock Purchase Plan share issuance, shares					(37,000)
Stock Option Plan share issuance, net	2,405		(1,736)		$ 4,141
Stock Option Plan share issuance, shares					(551,000)
Excess tax benefits from equity-based compensation	380		380
Restricted stock plan share issuance/forfeiture	(563)		(632)		$ (352)	$ 421
Restricted stock plan share issuance/forfeiture, shares					10,000	(98,000)
Deferred compensation plan share issuance	590		18		$ 572
Deferred compensation plan share issuance, shares					(76,000)
Purchase of stock	(1,406)				$ (1,406)
Purchase of stock, shares					182,000
Equity-based compensation	1,317		1,317
Net income (loss)	6,510			6,510
Dividends declared	(3,711)			(3,711)
Foreign currency adjustment	(1,875)						(1,875)
Pension loss adjustment, net of tax	2,828						2,828
Balance at Dec. 31, 2015	117,717	$ 270	125,226	121,798	$ (60,275)	$ (54,662)	(14,640)
Balance, shares at Dec. 31, 2015		27,018,000			8,014,000	3,265,000
Employee Stock Purchase Plan share issuance	215		(211)		$ 426
Employee Stock Purchase Plan share issuance, shares					(44,000)
Stock Option Plan share issuance, net	262		(820)		$ 1,082
Stock Option Plan share issuance, shares					(95,000)
Excess tax benefits from equity-based compensation	(233)		(233)
Restricted stock plan share issuance/forfeiture	(382)		(1,241)		$ (1,286)	$ 2,145
Restricted stock plan share issuance/forfeiture, shares					259,000	(503,000)
Deferred compensation plan share issuance	549		(400)		$ 949
Deferred compensation plan share issuance, shares					(105,000)
Purchase of stock	(1,244)				$ (1,244)
Purchase of stock, shares					287,000
Termination of stock trusts	7				$ (52,510)	$ 52,517
Termination of stock trusts, shares					2,762,000	(2,762,000)
Equity-based compensation	1,626		1,626
Net income (loss)	(34,638)			(34,638)
Dividends declared	(2,937)			(2,937)
Foreign currency adjustment	(758)						(758)
Pension loss adjustment, net of tax	(1,365)						(1,365)
Balance at Dec. 31, 2016	$ 78,819	$ 270	123,947	84,223	$ (112,858)		(16,763)
Balance, shares at Dec. 31, 2016	27,017,824	27,018,000			11,078,000
Employee Stock Purchase Plan share issuance	$ 155		(133)		$ 288
Employee Stock Purchase Plan share issuance, shares					(29,000)
Stock Option Plan share issuance, net	735		(1,346)		$ 2,080
Stock Option Plan share issuance, shares					(195,000)
Restricted stock plan share issuance/forfeiture	(328)		(2,870)		$ 2,543
Restricted stock plan share issuance/forfeiture, shares					(182,000)
Deferred compensation plan share issuance	450		(410)		$ 860
Deferred compensation plan share issuance, shares					(87,000)
Purchase of stock	(6,159)				$ (6,159)
Purchase of stock, shares					1,169,000
Equity-based compensation	1,059		1,059
Net income (loss)	806			806
Foreign currency adjustment	2,481						2,481
Pension loss adjustment, net of tax	606						606
Balance at Dec. 31, 2017	$ 78,624	$ 270	$ 120,247	$ 85,029	$ (113,246)		$ (13,676)
Balance, shares at Dec. 31, 2017	27,017,824	27,018,000			11,754,000