Discontinued Operations and Assets Held for Sale (Table Illustration of Number of Properties in Discontinued Operations) (Details)	1 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2020 buildings	Dec. 31, 2019 buildings	Dec. 31, 2018 buildings
Number of Real Estate Properties Held for Sale		2
Number of Real Estate Properties Sold	18	7	28	15
Total Properties Sold or Classified as Held for Sale		52