Real Estate Loans Receivable - Summary of Real Estate Loan Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Advances on real estate loans receivable:
Investments in new loans	$ 25,000	$ 15,436
Draws on existing loans	17,964	12,111
Net cash advances on real estate loans	42,964	27,547
Receipts on real estate loans receivable:
Loan payoffs	4,384	58,557
Principal payments on loans	1,965	32,174
Net cash receipts on real estate loans	6,349	90,731
Net cash advances (receipts) on real estate loans	36,615	(63,184)
Seniors Housing Operating
Advances on real estate loans receivable:
Investments in new loans	25,000	11,806
Draws on existing loans	0	0
Net cash advances on real estate loans	25,000	11,806
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	25,000	11,806
Triple-net
Advances on real estate loans receivable:
Investments in new loans	0	1,172
Draws on existing loans	12,956	12,111
Net cash advances on real estate loans	12,956	13,283
Receipts on real estate loans receivable:
Loan payoffs	4,384	58,557
Principal payments on loans	1,965	32,174
Net cash receipts on real estate loans	6,349	90,731
Net cash advances (receipts) on real estate loans	6,607	(77,448)
Outpatient Medical
Advances on real estate loans receivable:
Investments in new loans	0	2,458
Draws on existing loans	5,008	0
Net cash advances on real estate loans	5,008	2,458
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	$ 5,008	$ 2,458