Intangible Assets (Textual) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tenant Move-Outs Prior to End of the Lease Term [Member]
Finite Lived Intangible Assets [Line Items]
Intangible Assets Written Off Through Accelerated Amortization	$ 0.6	$ 0.6	$ 0.5