Deferred Financing and Leasing Costs (Finite-Lived Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items]
Unamortized market value intangible liabilities	$ 9.6	$ 4.4
Amortization of above and below Market Leases	$ (1.3)	$ (1.6)	$ (1.9)
Above Market Leases [Member]
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	3 years 1 month 25 days
Leases, Acquired-in-Place [Member]
Finite-Lived Intangible Assets [Line Items]
Remaining amortization period	5 years 6 months 4 days