Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2012	Jun. 30, 2012	Dec. 31, 2011
Operating, consolidated variable interest entities	$ 263,631	$ 263,631	$ 263,570
Accumulated depreciation and amortization, consolidated variable interest entities	8,497	8,497	4,991
Debt issuance costs, accumulated amortization	10,574	10,574	9,098
Mortgages payable, consolidated variable interest entities	$ 206,506	$ 206,506	$ 207,683
Preferred shares, authorized	15,000,000	15,000,000	15,000,000
Preferred shares, par	$ 0.01	$ 0.01	$ 0.01
Preferred Shares, percentage	5.417%	5.417%	5.417%
Preferred Shares, 5.417% Series 1 Cumulative Convertible liquidation preference	$ 25	$ 25	$ 25
Preferred shares, shares issued	399,896	399,896	399,896
Preferred shares, shares outstanding	399,896	399,896	399,896
Common shares of beneficial interest, par	$ 0.01	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000	100,000,000
Common shares of beneficial interest, shares issued	64,099,840	64,099,840	63,544,150
Common shares of beneficial interest, shares outstanding	64,099,840	64,099,840	63,544,150