Earnings Per Share (Schedule of Shares Issued and Outstanding) (Details)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Class of Stock [Line Items]
Less: Treasury Shares	(8,467,873)	(8,467,873)	(8,479,487)
Net shares Outstanding	31,595,452	31,410,429	31,341,615
Common Class A [Member]
Class of Stock [Line Items]
Common Stock, shares issued	36,827,227	36,642,204	36,585,004
Common Class B [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