Consolidated Statements of Equity (Parenthetical) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Dividends paid or accrued on Common Share of beneficial interest	$ 0.1625	$ 0.1625
Dividends paid or accrued on Series D Preferred Share	$ 0.57813	$ 0.57813
Accumulated Distributions in Excess of Net Income
Dividends paid or accrued on Common Share of beneficial interest	$ 0.1625	$ 0.1625
Dividends paid or accrued on Series D Preferred Share	$ 0.57813	$ 0.57813