Unaudited Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Total Stockholders' Equity	Common Stock Shares Outstanding Class A	Common Stock Shares Outstanding Class B	Capital in Excess of Par Value	Retained Earnings	Foreign Currency Translation Adjustment	Deferred Gain (Loss) on Available for Sale Securities	Deferred Gain (Loss) on Cash Flow Hedging	Pension and Postretirement Plan Adjustment
Balance, beginning of period at Dec. 31, 2014		$ 211,474	$ 5,662	$ 1,573	$ 0	$ 224,428	$ (2,699)	$ 1,463	$ 56	$ (19,009)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		662	37		625
Purchase of treasury shares		(16,009)	(292)		(625)	(15,092)
Net income (loss)	$ 752	752				752
Cash dividends on Class A and Class B common stock		(3,688)				(3,688)
Current period other comprehensive income (loss)		(1,796)					(1,162)	24	(658)
Reclassification adjustment to net income		699							274	425
Balance, end of period at Jun. 30, 2015		192,094	5,407	1,573	0	206,400	(3,861)	1,487	(328)	(18,584)
Balance, beginning of period at Dec. 31, 2015		201,138	5,265	1,572	0	217,745	(5,455)	1,480	(112)	(19,357)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		1,505	46		1,459
Purchase of treasury shares		(3,826)	(70)		(1,459)	(2,297)
Net income (loss)	$ 5,918	5,918				5,918
Cash dividends on Class A and Class B common stock		(3,638)				(3,638)
Current period other comprehensive income (loss)		(2,535)					(818)	164	(1,881)
Reclassification adjustment to net income		410							108	302
Balance, end of period at Jun. 30, 2016		$ 198,972	$ 5,241	$ 1,572	$ 0	$ 217,728	$ (6,273)	$ 1,644	$ (1,885)	$ (19,055)