SEGMENT INFORMATION - Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information
Capital expenditures	$ 84,704	$ 105,956
Operating Segments | Triple-Net Leased Properties
Segment Reporting Information
Capital expenditures	8,591	5,668
Operating Segments | Senior Living Operations
Segment Reporting Information
Capital expenditures	26,959	30,577
Operating Segments | Office Operations
Segment Reporting Information
Capital expenditures	$ 49,154	$ 69,711