Investments In Real Estate (Schedule Of Real Estate Property Acquisitions) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Business Acquisition [Line Items]
Acquisition, Amount	$ 117.3	[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
Cartech [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	London, England
Acquisition, Amount	3.6	[1]
Acquisition, Date Acquired	Apr. 02, 2013
MetCenter Business Park [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Austin, Texas	[2]
Acquisition, Amount	31.9	[1],[2]
Acquisition, Date Acquired	May 20, 2013	[2]
Liverpoolweg 10 [Member]
Business Acquisition [Line Items]
Acquisition, Metropolitan Area	Amsterdam, Netherlands
Acquisition, Amount	3.9	[1]
Acquisition, Date Acquired	Jun. 27, 2013
Fair value of contingent consideration	$ 3.9

[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.

[2] MetCenter Business Park consists of three buildings at 8201 E. Riverside Drive and three buildings at 7401 E. Ben White Boulevard in the Austin metropolitan area. MetCenter Business Park is considered one property for our property count.