Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Operating - consolidated variable interest entities	$ 282,303	$ 265,138
Accumulated depreciation and amortization of consolidated variable interest entities	26,618	19,086
Accumulated amortization of debt issuance costs	11,441	9,535
Mortgages payable - consolidated variable interest entities	$ 187,632	$ 202,782
Preferred shares, authorized	15,000,000	15,000,000
Preferred shares, par	$ 0.01	$ 0.01
Series 1 Cumulative Convertible Preferred interest rate	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	68,605,783	66,701,422
Common shares of beneficial interest, shares outstanding	68,605,783	66,701,422