SEGMENT INFORMATION - Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Segment Reporting Information [Line Items]
Capital expenditures	$ 129,589	$ 78,949	$ 438,719	$ 151,057
Operating Segments | Triple-Net Leased Properties
Segment Reporting Information [Line Items]
Capital expenditures	48,143	15,949	141,952	56,650
Operating Segments | Senior Living Operations
Segment Reporting Information [Line Items]
Capital expenditures	30,056	24,808	51,381	43,802
Operating Segments | Office Operations
Segment Reporting Information [Line Items]
Capital expenditures	$ 51,390	$ 38,192	$ 245,386	$ 50,605