Acquisitions and Dispositions (Summary of Significant Assumptions Utilized in Estimates) (Details)	6 Months Ended
	Jun. 30, 2018 $ / sqft
Minimum [Member]
Property, Plant and Equipment [Line Items]
Exit capitalization rate	4.25%
Maximum [Member]
Property, Plant and Equipment [Line Items]
Exit capitalization rate	4.91%
Industrial [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Net rental rate per square foot	6.50
Industrial [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Net rental rate per square foot	10.20