Real Estate Assets, Discontinued Operations and Assets Held for Sale (Table Illustration of Number of Properties in Discontinued Operations) (Details) - buildings	6 Months Ended	12 Months Ended
	Jun. 30, 2019	Dec. 31, 2018
Continuing Operations, Number of In-service Properties Held for Sale	2
Continuing Operations, Number of Real Estate Properties Sold	1	15
Total Properties Sold or Classified as Held for Sale	18