CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Shareholders' equity:
Preferred Shares of beneficial interest, par value	$ 0.01	$ 0.01
Preferred Shares of beneficial interest, shares authorized	100,000,000	100,000,000
Preferred Shares of beneficial interest, shares issued	745,600	1,000,000
Preferred Shares of beneficial interest, shares outstanding	745,600	1,000,000
Common Shares of beneficial interest, par value	$ 0.01	$ 0.01
Common Shares of beneficial interest, shares authorized	1,000,000,000	1,000,000,000
Common Shares of beneficial interest, shares issued	364,755,444	362,855,454
Common Shares of beneficial interest, shares outstanding	364,755,444	362,855,454