CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Dec. 31, 2012	Dec. 31, 2011
CONSOLIDATED BALANCE SHEETS
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	10,000,000	10,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	80,000,000	80,000,000
Common stock, shares issued	51,508,142	48,321,305
Common stock, shares outstanding	51,508,142	48,321,305
Excess stock, par value (in dollars per share)	$ 0.01	$ 0.01
Excess stock, shares authorized	10,000,000	10,000,000
Excess stock, shares issued	0	0
Excess stock, shares outstanding	0	0