Investments In Real Estate (Schedule Of Real Estate Property Acquisitions) (Details) In Millions, unless otherwise specified			9 Months Ended							0 Months Ended		9 Months Ended
	Sep. 30, 2012 USD ($)	Sep. 30, 2012 GBP (£)	Sep. 30, 2012 Convergence Business Park [Member] USD ($) property		Sep. 30, 2012 9333, 9355, 9377 Grand Avenue [Member] USD ($) property		Sep. 30, 2012 8025 North Interstate 35 [Member] USD ($)		Sep. 30, 2012 400 S. Akard Street [Member] USD ($)	Jul. 11, 2012 Sentrum Portfolio [Member] USD ($) property sqft	Jul. 11, 2012 Sentrum Portfolio [Member] GBP (£)	Sep. 30, 2012 Sentrum Portfolio [Member] USD ($)		Sep. 30, 2012 11900 East Cornell Avenue [Member] USD ($)
Business Acquisition [Line Items]
Acquisition, Metropolitan Area			Dallas, Texas	[1]	Chicago, Illinois	[2]	Austin, Texas	[3]	Dallas, Texas			London, England	[4]	Denver, Colorado
Acquisition, Amount	$ 1,462.2		$ 123.0	[1]	$ 22.3	[2]	$ 12.5	[3]	$ 75.0	$ 1,100.0	£ 734.6	$ 1,138.6	[4]	$ 90.8
Number of buildings			9		3
Number of properties			1		1					3	3
Secured mortgage loan assumed in acquisition							6.7
Acquisition, Date Acquired			Feb. 22, 2012	[1]	May 10, 2012	[2]	May 18, 2012	[3]	Jun. 13, 2012	Jul. 11, 2012	Jul. 11, 2012	Jul. 11, 2012	[4]	Sep. 14, 2012
Square footage of real estate property										733,000	733,000
Exchange rate										1.55	1.55
Adjustment to purchase price										29.0	18.7
Expected fair value of contingent consideration	91.3	56.5								87.6	56.5
Purchase adjustment related to deferred taxes										$ 106.3	£ 68.6

[1] Convergence Business Park is comprised of nine buildings along with undeveloped land. It is considered one property for our property count.

[2] 9333, 9355, 9377 Grand Avenue is comprised of three buildings. It is considered one property for our property count.

[3] In connection with the acquisition, we assumed a $6.7 million secured mortgage loan.

[4] On July 11, 2012, we completed the acquisition of a three-property data center portfolio, totaling approximately 733,000 square feet, located in the greater London area, referred to as the Sentrum Portfolio. The purchase price was £734.6 million (equivalent to approximately $1.1 billion based on the July 11, 2012 exchange rate of £1.00 to $1.55), which includes an £18.7 million (equivalent to approximately $29.0 million based on the July 11, 2012 exchange rate of £1.00 to $1.55) adjustment in the purchase price to reflect amounts associated with the early repayment of property debt. In addition, non-cash consideration of £56.5 million (or $87.6 million based on the July 11, 2012 exchange rate of £1.00 to $1.55) was recorded as the expected fair value of contingent consideration as required by prevailing accounting guidance. There was also a non-cash purchase adjustment related to deferred taxes, which amounted to £68.6 million (or $106.3 million based on the July 11, 2012 exchange rate of £1.00 to $1.55). The purchase price was paid in cash funded with proceeds from our common stock offering in July 2012 along with borrowings under our global revolving credit facility.