CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Preferred stock, par value per share	$ 5.0	$ 5.0
Preferred stock, shares authorized	2,000,000	2,000,000
Preferred stock, shares issued	0	0
Common Stock, shares outstanding	31,397,829	31,297,453
Treasury stock, shares	8,467,873	8,479,487
Class A Common Stock [Member]
Common Stock, par value per share	$ 0.001	$ 0.001
Common Stock, shares authorized	100,000,000	100,000,000
Common Stock, shares issued	36,629,604	36,540,842
Common Stock, shares outstanding	36,629,604	36,540,842
Class B Common Stock [Member]
Common Stock, par value per share	$ 0.001	$ 0.001
Common Stock, shares authorized	25,000,000	25,000,000
Common Stock, shares issued	3,236,098	3,236,098
Common Stock, shares outstanding	3,236,098	3,236,098