Unaudited Condensed Consolidated Statements of Changes in Equity (USD $)	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, 2012		$ 281,331,000	$ 6,771,000	$ 1,582,000	$ 24,612,000	$ 270,227,000	$ (574,000)	$ 292,000	$ (286,000)	$ (21,293,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		1,230,000	80,000		1,150,000
Purchase of treasury shares		(27,355,000)	(495,000)		(25,395,000)	(1,465,000)
Net income	21,894,000	21,894,000				21,894,000
Conversion of Class B to Class A shares			1,000	(1,000)
Cash dividends on Class A and Class B common stock: $0.7650 per share		(6,133,000)	0	0		(6,133,000)
Current period other comprehensive income (loss)		4,583,000					(85,000)	443,000	573,000	3,652,000
Current period curtailment gain into earnings, net of $578 tax expense in both the three and nine months ended September 30, 2013, respectively	(1,123,000)	(1,123,000)								(1,123,000)
Reclassification adjustment to net income (loss)		1,294,000							235,000	1,059,000
Balance, end of period at Sep. 30, 2013		275,721,000	6,357,000	1,581,000	367,000	284,523,000	(659,000)	735,000	522,000	(17,705,000)
Balance, beginning of period at Dec. 31, 2013		297,780,000	6,290,000	1,581,000	941,000	301,227,000	(803,000)	1,021,000	676,000	(13,153,000)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation		1,433,000	26,000		1,407,000
Purchase of treasury shares		(26,447,000)	(502,000)		(2,348,000)	(23,597,000)
Net income	2,551,000	2,551,000				2,551,000
Conversion of Class B to Class A shares			7,000	(7,000)
Cash dividends on Class A and Class B common stock: $0.7650 per share		(5,884,000)				(5,884,000)
Current period other comprehensive income (loss)		(1,246,000)					(656,000)	270,000	(860,000)
Current period curtailment gain into earnings, net of $578 tax expense in both the three and nine months ended September 30, 2013, respectively	0
Reclassification adjustment to net income (loss)		1,055,000							602,000	453,000
Balance, end of period at Sep. 30, 2014		$ 269,242,000	$ 5,821,000	$ 1,574,000	$ 0	$ 274,297,000	$ (1,459,000)	$ 1,291,000	$ 418,000	$ (12,700,000)