Equity (Details) (USD $)	3 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Dividends on common shares/units
Dividend per Share/Unit	$ 0.12	$ 0.12	$ 0.12	$ 0.12
Common Shares
Dividends Payable [Line Items]
Record Date	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011
Payable Date	Jan. 16, 2012	Oct. 17, 2011	Jul. 15, 2011	Apr. 15, 2011