Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2011	Dec. 31, 2010
Shareholders' equity:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,000,000	1,000,000
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Treasury stock, shares	1,639,843	1,639,843
Common Class A
Shareholders' equity:
Common Stock, Shares authorized	60,000,000	60,000,000
Common Stock, Shares outstanding	27,155,861	26,798,707
Common Class B
Shareholders' equity:
Common Stock, Shares authorized	20,000,000	20,000,000
Common Stock, Shares outstanding	10,725,472	10,700,044