Acquisitions and Dispositions (Summary of Significant Assumptions Utilized in Estimates) (Details)	3 Months Ended
	Mar. 31, 2018 $ / sqft
Minimum [Member]
Property, Plant and Equipment [Line Items]
Exit capitalization rate	4.50%
Maximum [Member]
Property, Plant and Equipment [Line Items]
Exit capitalization rate	4.50%
Industrial [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Net rental rate per square foot	9.12
Industrial [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Net rental rate per square foot	10.20