Intangible Assets and Liabilities (Narratives) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Intangible Assets Liabilities
Net amortization of intangibles	$ 9.6	$ 9.6	$ 19.0	$ 19.1
Minimum
Intangible Assets Liabilities
Finite-lived net lease intangibles, useful life			1 year
Maximum
Intangible Assets Liabilities
Finite-lived net lease intangibles, useful life			53 years
Maximum | Ground lease
Intangible Assets Liabilities
Finite-lived net lease intangibles, useful life			94 years