Real Estate Assets, Discontinued Operations and Assets Held for Sale (Table Illustration of Number of Properties in Discontinued Operations) (Details) - buildings	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Number of properties held for sale in discontinued operations		1
Number of properties sold in discontinued operations		80	0
Total number of properties in discontinued operations		81
Continuing Operations, Number of In-service Properties Held for Sale		1
Continuing Operations, Number of Real Estate Properties Sold		15	32
Continuing Operations, Number of Real Estate Properties Sold or Classified as Held for Sale		48
Number of Real Estate Properties Held for Sale		2
Number of Real Estate Properties Sold		95	32
Total Properties Sold or Classified as Held for Sale		129
Medical Office Portfolio Sale [Member]
Continuing Operations, Number of Real Estate Properties Sold		4
Total Properties Sold or Classified as Held for Sale	7	84