CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2011	Dec. 31, 2010
CONDENSED CONSOLIDATED BALANCE SHEETS
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	200,000,000	200,000,000
Common stock, shares issued	61,832,274	60,208,506
Common stock, shares outstanding	47,803,078	46,901,511
Treasury shares	14,029,196	13,306,995