Common Stock and Earnings per Share (Textual) (Details)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Class of Stock [Line Items]
Options exercisable, contractual term	4 years
Options granted in period, shares	0
Options outstanding, shares	0	0	0
Common Class A
Class of Stock [Line Items]
Common stock, shares authorized	25,000,000
Treasury sock, shares	1,430,843	1,409,915
Common stock available for grant, shares	80,701	80,701	80,701
Common Class B
Class of Stock [Line Items]
Common stock, shares authorized	6,756,176
Common stock available for grant, shares	80,100	80,100	80,100
Stock Options [Member]
Class of Stock [Line Items]
Options exercisable, expiration date	10 years