SEGMENT INFORMATION (Details 2) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Total assets	$ 24,439,871	$ 21,226,171
Percentage of total assets	100.00%	100.00%
Triple-Net Leased Properties
Segment Reporting Information [Line Items]
Total assets	9,684,808	9,176,159
Percentage of total assets	39.60%	43.20%
Senior Living Operations
Segment Reporting Information [Line Items]
Total assets	8,329,612	7,421,924
Percentage of total assets	34.10%	35.00%
MOB Operations
Segment Reporting Information [Line Items]
Total assets	5,150,741	3,526,217
Percentage of total assets	21.10%	16.60%
All Other
Segment Reporting Information [Line Items]
Total assets	$ 1,274,710	$ 1,101,871
Percentage of total assets	5.20%	5.20%