Significant Acquisitions and Dispositions (Summary of Significant Assumptions Utilized in Estimates) (Details) - $ / sqft	Dec. 31, 2018	Dec. 31, 2017
Industrial [Member] | Minimum [Member]
Fair Value Measurement With Unobservable Inputs Rental Rate Per Square Foot	6.50	3.50
Industrial [Member] | Maximum [Member]
Fair Value Measurement With Unobservable Inputs Rental Rate Per Square Foot	10.20	10.00
Measurement Input, Cap Rate [Member] | Minimum [Member]
Fair Value Inputs, Capitalization Rate	3.80%	4.03%
Measurement Input, Cap Rate [Member] | Maximum [Member]
Fair Value Inputs, Capitalization Rate	4.91%	5.65%