CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Preferred stock , Authorized shares	5,000,000	5,000,000
Preferred stock , par value	$ 0.01	$ 0.01
Preferred stock , Issued
Common stock, Authorized shares	150,000,000	150,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, Issued shares	87,732,405	85,968,630
Treasury stock, shares	5,005,518	2,734,747