Real Estate Investments - Mortgage Loans Activity (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Mortgage Loans
Originations and fundings under mortgage loans receivable	$ 366	$ 1,454
Scheduled principal payments received	(65)	(65)
Mortgage loan premium amortization	(1)
(Provision for) recovery of loan loss reserve	(3)	(14)
Net increase (decrease) in mortgage loans receivable	$ 297	$ 1,375