Consolidated Statement of Equity (Parenthetical) (USD $)	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Dividends paid or accrued on Common Shares of Beneficial Interest	$ 0.325	$ 0.325
Dividends paid or accrued on Series D Preferred Share	$ 1.15625	$ 1.15625
Accumulated Distributions in Excess of Net Income [Member]
Dividends paid or accrued on Common Shares of Beneficial Interest	$ 0.325	$ 0.325
Dividends paid or accrued on Series D Preferred Share	$ 1.15625	$ 1.15625