Loans Held for Investment - Loan Activity (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2020
SEC Schedule, 12-29, Real Estate Companies, Investment in Movement in Mortgage Loans on Real Estate [Roll Forward]
Principal, beginning balance	$ 272,234	$ 242,899
Deferred fees, beginning balance	(747)	(821)
Carrying value, beginning balance	271,487	242,078
Additional funding	6,250	9,459
Principal, originations		26,126
Deferred fees, originations		(388)
Carrying value, originations		25,738
Net amortization of deferred fees	488	950
Principal, ending balance	278,484	278,484
Deferred fees, ending balance	(259)	(259)
Carrying value, ending balance	$ 278,225	$ 278,225