Capital Stock (Details)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Capital Stock [Roll Forward]
Exercise of stock options	178,744	399,144	490,325
Stock Issued During Period, Shares, Restricted Stock Award, Forfeited	4,900	5,600	17,325
Common Stock Shares
Capital Stock [Roll Forward]
Beginning Balance	33,559,000	33,048,000	32,449,000
Exercise of stock options	180,000	399,000	490,000
Restricted stock awards	96,000	87,000	109,000
Purchase of shares for treasury	0	0
Conversion of Class B to Common		25,000
Ending Balance	33,835,000	33,559,000	33,048,000
Class B Shares
Capital Stock [Roll Forward]
Beginning Balance	1,086,000	1,111,000	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	1,111,000
Treasury Shares
Capital Stock [Roll Forward]
Beginning Balance	(2,319,000)	(1,834,000)	(1,424,000)
Exercise of stock options	0	(247,000)	(386,000)
Restricted stock awards	(31,000)	(33,000)	(24,000)
Purchase of shares for treasury	(750,000)	(205,000)
Conversion of Class B to Common		0
Ending Balance	(3,100,000)	(2,319,000)	(1,834,000)