Significant Acquisitions and Dispositions (Summary of Significant Assumptions Utilized in Estimates) (Details)	Dec. 31, 2019 buildings $ / sqft	Dec. 31, 2018 buildings $ / sqft	Dec. 31, 2017 buildings
Number of Real Estate Properties | buildings	6	9	28
Industrial [Member] | Minimum [Member]
Fair Value Measurement With Unobservable Inputs Rental Rate Per Square Foot	5.90	6.50
Industrial [Member] | Maximum [Member]
Fair Value Measurement With Unobservable Inputs Rental Rate Per Square Foot	15.60	10.20
Measurement Input, Cap Rate [Member] | Minimum [Member]
Fair Value Inputs, Capitalization Rate	4.23%	3.80%
Measurement Input, Cap Rate [Member] | Maximum [Member]
Fair Value Inputs, Capitalization Rate	5.32%	4.91%