Consolidated Statements of Equity (Unaudited) (Parenthetical) (USD $)	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
Dividends paid or accrued per Common Share of Beneficial Interest	$ 0.325	$ 0.325
Dividends paid or accrued per Series C Preferred Share	$ 0.8125	$ 0.8125
Accumulated Distribution in Excess of Net Income
Dividends paid or accrued per Common Share of Beneficial Interest	$ 0.325	$ 0.325
Dividends paid or accrued per Series C Preferred Share	$ 0.8125	$ 0.8125