Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data	Jun. 30, 2011	Dec. 31, 2010
Tenant and other receivables, allowance (in dollars)	$ 16,548	$ 12,981
Deferred rents receivable, allowance (in dollars)	29,352	30,834
Debt and preferred equity investments, discount (in dollars)	19,351	42,937
Debt and preferred equity investments, allowance (in dollars)	$ 41,800	$ 61,361
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	160,000	160,000
Common stock, shares issued	87,723	81,675
Common stock, shares outstanding	87,723	81,675
Treasury stock, shares	3,426	3,369
Series C preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25.00	$ 25.00
Preferred stock, shares issued	11,700	11,700
Preferred stock, shares outstanding	11,700	11,700
Series D preferred stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)	$ 25.00	$ 25.00
Preferred stock, shares issued	4,000	4,000
Preferred stock, shares outstanding	4,000	4,000