Consolidated Balance Sheets (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Series A Preferred Stock	Dec. 31, 2012 Series A Preferred Stock	Jun. 30, 2013 Series B Preferred Stock	Dec. 31, 2012 Series B Preferred Stock
Preferred stock, par value (in dollars per share)			$ 0.01	$ 0.01	$ 0.01	$ 0.01
Preferred stock, shares authorized			10,000,000	10,000,000	10,000,000	10,000,000
Preferred stock, shares issued			2,760,000	2,760,000	2,800,000	2,800,000
Preferred stock, shares outstanding			2,760,000	2,760,000	2,800,000	2,800,000
Preferred stock, liquidation preference (in dollars per share)			$ 25.00	$ 25.00	$ 25.00	$ 25.00
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	42,235,676	35,698,582
Common stock, shares outstanding	42,235,676	35,698,582