CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010
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
Treasury stock, shares	8,479,487	8,484,528
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	36,515,942	36,442,209
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