Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified			12 Months Ended		12 Months Ended		12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Series C Preferred Stock	Dec. 31, 2010 Series C Preferred Stock	Dec. 31, 2011 Series D Preferred Stock	Dec. 31, 2010 Series D Preferred Stock	Dec. 31, 2011 Series H Preferred Units
Tenant and other receivables, allowance (in dollars)	$ 16,772	$ 12,981
Deferred rents receivable, allowance (in dollars)	29,156	30,834
Debt and preferred equity investments, discount (in dollars)	24,996	42,937
Debt and preferred equity investments, allowance (in dollars)	$ 50,175	$ 61,361
Preferred Units (as a percent)			7.625%		7.875%		6.00%
Preferred Units, par value (in dollars per share)							$ 0.01
Preferred units, shares issued							80
Preferred Units, shares outstanding							80
Preferred units, liquidation preference (in dollars per share)							$ 25.00
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Preferred stock, liquidation preference (in dollars per share)			$ 25.00	$ 25.00	$ 25.00	$ 25.00
Preferred stock, shares issued			11,700	11,700	4,000	4,000
Preferred stock, shares outstanding			11,700	11,700	4,000	4,000
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	160,000	160,000
Common stock, shares issued	89,210	81,675
Common stock, shares outstanding	89,210	81,675
Treasury stock, shares	3,427	3,369