Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Dec. 31, 2010
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	30,000,000	30,000,000
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	150,000,000	150,000,000
Common stock, shares issued	58,464,412	52,349,670
Common stock, shares outstanding	58,464,412	52,349,670
Series A Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Preferred stock dividend rate percentage	7.45%	7.45%
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,500,000	1,500,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Series E Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Preferred stock dividend rate percentage	7.80%	7.80%
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	1,610,000	1,610,000
Preferred stock, shares issued	1,610,000	1,610,000
Preferred stock, shares outstanding	1,610,000	1,610,000
Preferred Stock Liquidation preference	$ 40,250	$ 40,250
Series F Cumulative Redeemable Preferred Stock
Preferred stock, $.01 par value, 30,000,000 shares authorized:
Preferred stock dividend rate percentage	7.50%	7.50%
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	3,450,000	3,450,000
Preferred stock, shares issued	3,450,000	3,450,000
Preferred stock, shares outstanding	3,450,000	3,450,000
Preferred Stock Liquidation preference	$ 86,250	$ 86,250