Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Operating, consolidated variable interest entities	$ 271,468	$ 78,846
Assets held for sale/disposal (discontinued operations), consolidated variable interest entities	0	18,311
Accumulated depreciation and amortization, consolidated variable interest entities	4,991	4,431
Debt issuance costs, accumulated amortization	9,098	9,075
Mortgages payable, consolidated variable interest entities	$ 207,683	$ 22,785
Preferred shares, authorized	15,000,000	15,000,000
Preferred shares, par	$ 0.01	$ 0.01
Preferred Shares, percentage	5.417%	5.417%
Preferred Shares, 5.417% Series 1 Cumulative Convertible liquidation preference	$ 25	$ 25
Preferred shares, shares issued	399,896	399,896
Preferred shares, shares outstanding	399,896	399,896
Common shares of beneficial interest, par	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000
Common shares of beneficial interest, shares issued	63,544,150	61,526,418
Common shares of beneficial interest, shares outstanding	63,544,150	61,526,418