Earnings Per Share (Schedule of Shares Issued and Outstanding) (Details)	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011
Class of Stock [Line Items]
Less: Treasury Shares	(8,479,487)	(8,479,487)	(8,484,528)
Net shares Outstanding	31,341,615	31,297,453	31,256,862
Class A Common Stock [Member]
Class of Stock [Line Items]
Common Stock, shares issued	36,585,004	36,540,842	36,505,292
Class B Common Stock [Member]
Class of Stock [Line Items]
Common Stock, shares issued	3,236,098	3,236,098	3,236,098
Net shares Outstanding	3,236,098	3,236,098