Rental Properties Disposition (Details) In Millions, unless otherwise specified	3 Months Ended	0 Months Ended		3 Months Ended
	Dec. 31, 2011 USD ($)	Mar. 29, 2011 Toronto Dundas Square Member CAD	Feb. 03, 2011 Toronto Dundas Square Member USD ($)	Dec. 31, 2011 Toronto Dundas Square Member CAD	Feb. 03, 2011 Toronto Dundas Square Member CAD
Significant Acquisitions and Disposals [Line Items]
Gross Sales Proceeds From Sale Of Real Estate		226
Net Sales Proceeds From Sale Of Real Estate		222.7
Escrow Deposits Related to Property Sales		15.3
Foreign Currency Fair Value Hedge Asset at Fair Value			201.5		200.0
Gains (Losses) on Sales of Investment Real Estate			18.3
Payments for (Proceeds from) Real Estate Held-for-investment				13.1
Real Estate Disposals Transaction Liability Balance				2.2
Gains Losses On Sales Or Acquisitions Of Real Estate	1.2
Real Estate Related Assets				2.9
Real Estate Related Liabilites				5.6