Balance Sheet Parenthetical (USD $)	Sep. 30, 2011	Dec. 31, 2010
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Preferred stock, shares issued	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	120,000,000	120,000,000
Common stock, shares issued	60,223,170	59,232,486
Common stock, shares outstanding	32,781,333	58,287,697
Treasury stock, shares	27,441,837	944,789