SEGMENT INFORMATION - Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Segment Reporting Information
Capital expenditures	$ 295,942	$ 104,012	$ 380,646	$ 209,968
Operating Segments | Triple-Net Leased Properties
Segment Reporting Information
Capital expenditures	5,656	15,340	14,247	21,008
Operating Segments | Senior Living Operations
Segment Reporting Information
Capital expenditures	37,494	24,177	64,453	54,754
Operating Segments | Office Operations
Segment Reporting Information
Capital expenditures	$ 252,792	$ 64,495	$ 301,946	$ 134,206