CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Common stock, shares authorized	200,000,000	200,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares outstanding	68,469,444	68,378,984
Treasury stock, shares	1,873,870	1,870,205