Real Estate Loans Receivable - Summary of Real Estate Loan Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Advances on real estate loans receivable:
Investments in new loans	$ 30,000	$ 37,427
Draws on existing loans	52,345	29,709
Net cash advances on real estate loans	82,345	67,136
Receipts on real estate loans receivable:
Loan payoffs	29,020	116,161
Principal payments on loans	3,110	33,431
Net cash receipts on real estate loans	32,130	149,592
Net cash advances (receipts) on real estate loans	50,215	(82,456)
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	10,628
Draws on existing loans	33,955	29,709
Net cash advances on real estate loans	58,955	40,337
Receipts on real estate loans receivable:
Loan payoffs	29,020	116,161
Principal payments on loans	3,110	33,431
Net cash receipts on real estate loans	32,130	149,592
Net cash advances (receipts) on real estate loans	26,825	(109,255)
Outpatient Medical
Advances on real estate loans receivable:
Investments in new loans	5,000	14,993
Draws on existing loans	18,390	0
Net cash advances on real estate loans	23,390	14,993
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	$ 23,390	$ 14,993