CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Sep. 30, 2012	Dec. 31, 2011
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	39,513,351	39,439,115
Common stock, shares outstanding	35,954,925	37,907,575
Treasury stock, shares	3,558,426	1,531,540