Investments In Real Estate (Schedule Of Real Estate Property Acquisitions) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Business Acquisition [Line Items]
Acquisition, Amount	$ 77.9	[1]
17201 Waterview Parkway [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Dallas, Texas
Acquisition, Amount	8.5	[1]
Acquisition, Date Acquired	Jan. 31, 2013
1900 S. Price Road [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Phoenix, Arizona
Acquisition, Amount	24.0	[1]
Acquisition, Date Acquired	Jan. 31, 2013
371 Gough Road [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Toronto, Canada
Acquisition, Amount	8.4	[1]
Acquisition, Date Acquired	Mar. 12, 2013
1500 Towerview Road [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Minneapolis, Minnesota
Acquisition, Amount	$ 37.0	[1]
Acquisition, Date Acquired	Mar. 27, 2013

[1] Purchase prices are all in U.S. dollars. Purchase prices for acquisitions outside the United States are based on the exchange rate at the date of acquisition.