CONCENTRATION OF CREDIT RISK - Triple-Net Leased Properties (Details) - Customer Concentration Risk	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Revenues | Brookdale Senior Living
Concentration Risk
Concentration percentage	4.00%	4.60%
Revenues | Ardent
Concentration Risk
Concentration percentage	3.30%	3.00%
Revenues | Kindred
Concentration Risk
Concentration percentage	3.60%	3.30%
NOI | Brookdale Senior Living
Concentration Risk
Concentration percentage	8.80%	8.60%
NOI | Ardent
Concentration Risk
Concentration percentage	7.20%	5.70%
NOI | Kindred
Concentration Risk
Concentration percentage	7.80%	6.20%