Capital Stock (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Capital Stock [Roll Forward]
Exercise of stock options	(9,417)	(178,744)	(399,144)
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	10,631	4,900	5,600
Common Stock, Dividends, Per Share, Declared and Paid	$ 0.05
Class B Common Stock, Dividends, Per Share, Declared and Paid	$ 0.045
Common Stock Shares
Capital Stock [Roll Forward]
Beginning Balance	33,835,000	33,559,000	33,048,000
Exercise of stock options	10,000	180,000	399,000
Restricted stock awards	107,000	96,000	87,000
Purchase of shares for treasury		0	0
Conversion of Class B to Common			25,000
Ending Balance	33,952,000	33,835,000	33,559,000
Class B Shares
Capital Stock [Roll Forward]
Beginning Balance	1,086,000	1,086,000	1,111,000
Exercise of stock options	0	0	0
Restricted stock awards	0	0	0
Purchase of shares for treasury		0	0
Conversion of Class B to Common			(25,000)
Ending Balance	1,086,000	1,086,000	1,086,000
Treasury Shares
Capital Stock [Roll Forward]
Beginning Balance	(3,100,000)	(2,319,000)	(1,834,000)
Exercise of stock options	(8,000)	0	(247,000)
Restricted stock awards	(27,000)	(31,000)	(33,000)
Purchase of shares for treasury		(750,000)	(205,000)
Conversion of Class B to Common			0
Ending Balance	(3,135,000)	(3,100,000)	(2,319,000)