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		146	34		112
Purchase of treasury shares		(6,911)	(121)		(112)	(6,678)
Net income	$ 1,027	1,027				1,027
Cash dividends on Class A and Class B common stock		(1,850)				(1,850)
Current period other comprehensive income (loss)		(1,380)					(823)	38	(595)
Reclassification adjustment to net income		444							185	259
Balance, end of period at Mar. 31, 2015		202,950	5,575	1,573	0	216,927	(3,522)	1,501	(354)	(18,750)
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		754	42		712
Conversion of Class B to Class A shares			1	(1)
Net income	$ 2,802	2,802				2,802
Cash dividends on Class A and Class B common stock		(1,804)				(1,804)
Current period other comprehensive income (loss)		(1,095)					207	65	(1,367)
Reclassification adjustment to net income		224							75	149
Balance, end of period at Mar. 31, 2016		$ 202,019	$ 5,308	$ 1,571	$ 712	$ 218,743	$ (5,248)	$ 1,545	$ (1,404)	$ (19,208)