Investments In Real Estate (Schedule Of Pro Forma Operating Revenues And Operating Income) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2012		Sep. 30, 2011		Sep. 30, 2012		Sep. 30, 2011
Investments In Real Estate [Abstract]
Pro Forma, Operating Revenue	$ 345.9	[1]	$ 305.4	[1]	$ 995.9	[1]	$ 887.1	[1]
Pro forma, Operating Income	$ 98.4	[1]	$ 84.1	[1]	$ 297.8	[1]	$ 260.5	[1]

[1] These unaudited pro forma results do not purport to be indicative of what operating results would have been had the acquisition occurred on January 1, 2011, and may not be indicative of future operating results. The pro forma results exclude transaction expenses.