Loans Held for Investment - Property Type (Details)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 402,687,438	$ 377,388,317
Carrying value	$ 402,969,513	$ 378,612,768
Percent Of Loan Portfolio Holdings	100.00%	100.00%
Allowance for Loan and Lease Losses, Real Estate	$ (1,144,994)	$ 0
Percent Of Allowance Of Loan Losses	(0.003)	0
Office
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 143,941,260	$ 142,055,845
Carrying value	$ 143,879,383	$ 141,870,355
Percent Of Loan Portfolio Holdings	35.70%	40.00%
Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 83,318,419	$ 76,640,369
Carrying value	$ 83,907,425	$ 77,136,016
Percent Of Loan Portfolio Holdings	20.80%	20.00%
Student housing
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 75,155,569	$ 58,049,717
Carrying value	$ 75,608,070	$ 58,553,496
Percent Of Loan Portfolio Holdings	18.80%	20.00%
Hotel
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 47,859,380	$ 46,598,011
Carrying value	$ 48,029,027	$ 46,731,939
Percent Of Loan Portfolio Holdings	11.90%	10.00%
Infill land
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 34,812,810	$ 36,444,375
Carrying value	$ 34,992,810	$ 36,624,375
Percent Of Loan Portfolio Holdings	8.70%	10.00%
Condominium
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 10,600,000	$ 10,600,000
Carrying value	$ 10,697,792	$ 10,696,587
Percent Of Loan Portfolio Holdings	2.70%	0.00%
Industrial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Principal Balance	$ 7,000,000	$ 7,000,000
Carrying value	$ 7,000,000	$ 7,000,000
Percent Of Loan Portfolio Holdings	1.70%	0.00%