SEGMENT INFORMATION - Capital Expenditures (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information
Payments for Capital Improvements	$ 88,482	$ 200,557
Operating Segments | Triple-Net Leased Properties
Segment Reporting Information
Payments for Capital Improvements	8,218	7,685
Operating Segments | Senior Living Operations
Segment Reporting Information
Payments for Capital Improvements	48,717	51,884
Operating Segments | Office Operations
Segment Reporting Information
Payments for Capital Improvements	$ 31,547	$ 140,988