Loans Receivable - Summary of Real Estate Loan Activity (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Advances on loans receivable:
Net cash advances on loans receivable	$ 216,307	$ 90,856
Receipts on loans receivable:
Net cash receipts on loans receivable	14,345	57,125
Seniors Housing Operating
Advances on loans receivable:
Investments in new loans	194,942	36,024
Draws on existing loans	21,365	54,832
Net cash advances on loans receivable	216,307	90,856
Receipts on loans receivable:
Loan payoffs	0	37,686
Principal payments on loans	14,345	19,439
Net cash receipts on loans receivable	14,345	57,125
Net cash advances (receipts) on loans receivable	$ 201,962	$ 33,731