Real Estate Assets, Discontinued Operations and Assets Held for Sale (Table Illustration of Number of Properties in Discontinued Operations) (Details) - buildings	9 Months Ended	12 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Continuing Operations, Number of In-service Properties Held for Sale	1
Continuing Operations, Number of Real Estate Properties Sold	27	15
Total Properties Sold or Classified as Held for Sale	43