Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Share data	Jun. 30, 2011	Dec. 31, 2010
Condensed Consolidated Balance Sheets
Receivables, allowance	$ 1,934	$ 1,750
Accrued rental income, allowance	4,364	3,609
Debt costs, accumulated amortization	13,674	11,198
Notes payable - convertible, unamortized discount	8,967	12,201
Notes payable, unamortized discount	$ 1,017	$ 1,118
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	15,000,000	15,000,000
Series C, depositary shares issued	3,680,000	3,680,000
Series C, depositary shares outstanding	3,680,000	3,680,000
Series C, stated liquidation value per share	$ 25	$ 25
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	190,000,000	190,000,000
Common stock, shares issued and outstanding	86,034,430	83,613,289
Excess stock, par value	$ 0.01	$ 0.01
Excess stock, shares authorized	205,000,000	205,000,000
Excess stock, shares issued	0	0
Excess stock, shares outstanding	0	0