Real Estate Loans Receivable - Summary of Real Estate Loan Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Advances on loans receivable:
Net cash advances on loans receivable	$ 10,441	$ 45,452
Receipts on loans receivable:
Net cash receipts on loans receivable	10,045	7,210
Seniors Housing Operating
Advances on loans receivable:
Investments in new loans	0	25,000
Draws on existing loans	10,441	20,452
Net cash advances on loans receivable	10,441	45,452
Receipts on loans receivable:
Loan payoffs	0	4,384
Principal payments on loans	10,045	2,826
Net cash receipts on loans receivable	10,045	7,210
Net cash advances (receipts) on loans receivable	$ 396	$ 38,242