Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2016	Dec. 31, 2015
Statement of Financial Position [Abstract]
Operating real estate, consolidated variable interest entities	$ 1,219,223	$ 1,192,336
Accumulated depreciation and amortization, consolidated variable interest entities	200,877	176,057
Mortgages payable, consolidated variable interest entities	$ 441,294	$ 448,315
Preferred shares, authorized	15,000,000	15,000,000
Preferred shares, par value	$ 0.01	$ 0.01
Series 1 Cumulative Convertible Preferred Shares 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 value	$ 0.01	$ 0.01
Common shares of beneficial interest, shares authorized	100,000,000	100,000,000
Common shares of beneficial interest, shares issued	71,782,989	69,493,392
Common shares of beneficial interest, shares outstanding	71,782,989	69,493,392