Intangible Assets and Liabilities (Narratives) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Intangible Assets And Liabilities [Abstract]
Net amortization of intangibles	$ 8.9	$ 7.3	$ 26.3	$ 20.5
Maximum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life			40 years 0 months 0 days
Maximum | Ground lease
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life			94 years 0 months 0 days
Minimum
Finite Lived Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life			1 year 0 months 0 days