Schedule IV - Movement in Mortgage Loans on Real Estate (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Beginning Balance	$ 10,164	$ 20,294	$ 22,764
Deductions during the year:
Early payoff of loan investment	0	0	(1,502)
Sale of loan investments	(9,946)	(8,256)	0
Principal payments received on loan investments	(106)	(897)	(904)
Amortization of discount and premiums	(19)	15	(64)
Valuation allowance	(93)	(992)	0
Ending Balance	$ 0	$ 10,164	$ 20,294