CONCENTRATION OF CREDIT RISK (Details)	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Concentration of credit risk
Number of states	46
Number of Canadian provinces	2
Revenue concentration risk percentage	10.00%
Brookdale Senior Living
Concentration of credit risk
Percentage of total revenues derived by third party	7.40%	10.90%
Percentage of net operating income derived from lease agreements	11.90%	16.50%
Total gross book value of properties | Seniors housing communities
Concentration of credit risk
Percentage of real estate investments based on gross book value	66.10%
Total gross book value of properties | Skilled nursing facilities, hospitals, MOBs and other healthcare assets
Concentration of credit risk
Percentage of real estate investments based on gross book value	33.90%
Total gross book value of properties | ATRIA
Concentration of credit risk
Percentage of real estate investments based on gross book value	19.30%
Total gross book value of properties | SUNRISE
Concentration of credit risk
Percentage of real estate investments based on gross book value	14.50%
Total gross book value of properties | Brookdale Senior Living
Concentration of credit risk
Percentage of real estate investments based on gross book value	12.20%
Total gross book value of properties | KINDRED
Concentration of credit risk
Percentage of real estate investments based on gross book value	5.00%
Total revenues | Minimum | Two states
Concentration of credit risk
Number of states accounting for more than 10% of total revenues	2
Total revenues | KINDRED
Concentration of credit risk
Percentage of total revenues derived by third party	11.10%	23.00%
Total NOI | Minimum | California
Concentration of credit risk
Number of states accounting for more than 10% of total revenues	1
Total NOI | KINDRED
Concentration of credit risk
Percentage of net operating income derived from lease agreements	18.00%	35.00%