Real Estate Loans Receivable - Summary of Real Estate Loan Activity (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Advances on real estate loans receivable:
Investments in new loans	$ 30,000	$ 27,109
Draws on existing loans	32,935	21,182
Net cash advances on real estate loans	62,935	48,291
Receipts on real estate loans receivable:
Loan payoffs	4,384	58,557
Principal payments on loans	2,456	32,870
Net cash receipts on real estate loans	6,840	91,427
Net cash advances (receipts) on real estate loans	56,095	(43,136)
Seniors Housing Operating
Advances on real estate loans receivable:
Investments in new loans		11,806
Draws on existing loans		0
Net cash advances on real estate loans		11,806
Receipts on real estate loans receivable:
Loan payoffs		0
Principal payments on loans		0
Net cash receipts on real estate loans		0
Net cash advances (receipts) on real estate loans		11,806
Triple-net
Advances on real estate loans receivable:
Investments in new loans	25,000	8,281
Draws on existing loans	20,051	21,182
Net cash advances on real estate loans	45,051	29,463
Receipts on real estate loans receivable:
Loan payoffs	4,384	58,557
Principal payments on loans	2,456	32,870
Net cash receipts on real estate loans	6,840	91,427
Net cash advances (receipts) on real estate loans	38,211	(61,964)
Outpatient Medical
Advances on real estate loans receivable:
Investments in new loans	5,000	7,022
Draws on existing loans	12,884	0
Net cash advances on real estate loans	17,884	7,022
Receipts on real estate loans receivable:
Loan payoffs	0	0
Principal payments on loans	0	0
Net cash receipts on real estate loans	0	0
Net cash advances (receipts) on real estate loans	$ 17,884	$ 7,022