Intangible Assets and Liabilities (Narratives) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Intangible Assets And Liabilities [Abstract]
Net amortization of intangibles	$ 38.0	$ 35.5	$ 28.3
Minimum
Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life	1 year
Maximum
Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life	53 years
Maximum | Ground lease
Intangible Assets Liabilities [Line Items]
Finite-lived net lease intangibles, useful life	94 years