CONCENTRATION OF CREDIT RISK - Triple-Net Leased Properties (Details) - board_member	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Ardent
Concentration Risk
Ownership interests accounted for under the equity method	9.80%
Number of Board Members Appointed	1
Number of Board Members	11
Brookdale Senior Living | Revenues
Concentration Risk
Concentration percentage	4.80%	4.60%
Brookdale Senior Living | NOI
Concentration Risk
Concentration percentage	8.80%	8.10%
Ardent | Revenues
Concentration Risk
Concentration percentage	3.10%	3.00%
Ardent | NOI
Concentration Risk
Concentration percentage	5.70%	5.40%
Kindred | Revenues
Concentration Risk
Concentration percentage	3.40%	3.40%
Kindred | NOI
Concentration Risk
Concentration percentage	6.20%	6.10%