SEGMENT INFORMATION - Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Reporting Information
Capital expenditures	$ 888,791	$ 129,205	$ 1,269,437	$ 339,173
Operating Segments | Triple-Net Leased Properties
Segment Reporting Information
Capital expenditures	13,558	10,773	27,805	31,781
Operating Segments | Senior Living Operations
Segment Reporting Information
Capital expenditures	780,837	36,138	845,290	90,892
Operating Segments | Office Operations
Segment Reporting Information
Capital expenditures	$ 94,396	$ 82,294	$ 396,342	$ 216,500