Unaudited Condensed Consolidated Statements of Changes in Equity (USD $) In Thousands, unless otherwise specified	Total	Total Stockholders' Equity	Common Stock Common Class A	Common Stock Common 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, 2012		$ 281,331	$ 6,771	$ 1,582	$ 24,612	$ 270,227	$ (574)	$ 292	$ (286)	$ (21,293)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		865	78		787
Purchase of treasury shares		(21,608)	(394)		(21,214)
Net income (loss)	9,569	9,569				9,569
Cash dividends on Class A and Class B common stock: $0.5075 per share		(4,134)				(4,134)
Current period other comprehensive income (loss)		925					(64)	292	697	0
Reclassification adjustment to net income (loss)		1,078							273	805
Balance, end of period at Jun. 30, 2013		268,026	6,455	1,582	4,185	275,662	(638)	584	684	(20,488)
Balance, beginning of period at Dec. 31, 2013		297,780	6,290	1,581	941	301,227	(803)	1,021	676	(13,153)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		862	22		840
Purchase of treasury shares		(14,247)	(266)		(1,781)	(12,200)
Net income (loss)	(5,148)	(5,148)				(5,148)
Cash dividends on Class A and Class B common stock: $0.5075 per share		(3,957)				(3,957)
Current period other comprehensive income (loss)		(1,129)					84	237	(1,450)
Reclassification adjustment to net income (loss)		626							353	273
Balance, end of period at Jun. 30, 2014		$ 274,787	$ 6,046	$ 1,581	$ 0	$ 279,922	$ (719)	$ 1,258	$ (421)	$ (12,880)