Earnings Per Share (Schedule of Shares Issued and Outstanding) (Details)	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Jun. 30, 2012
Class of Stock [Line Items]
Less: Treasury Shares	(8,463,635)	(8,467,873)	(8,467,873)	(8,467,873)
Net shares Outstanding	31,647,590	31,595,452		31,357,529
Common Class A [Member]
Class of Stock [Line Items]
Common Stock, shares issued	36,875,127	36,827,227	36,642,204	36,589,304
Common Class B [Member]
Class of Stock [Line Items]
Common Stock, shares issued	3,236,098	3,236,098	3,236,098	3,236,098
Net shares Outstanding	3,236,098		3,236,098