Real Estate Investments - Mortgage Loans Activity (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Mortgage Loans
Originations and funding under mortgage loans receivable	$ 1,026,000	$ 158,000
Application of interest reserve	1,223,000
Scheduled principal payments received	(125,000)	(125,000)
Mortgage loan premium amortization	(2,000)	(2,000)
Provision for loan loss reserve	(21,000)
Net (decrease) increase in mortgage loans receivable	2,101,000	31,000
Interest receivable	41,165,000		$ 39,522,000
Write-off of accrued interest receivable	$ 0	$ 0