Fair Value Measurements - Valuation techniques (Details)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure	$ 399,609,378	$ 379,160,415
Other Liabilities, Fair Value Disclosure		229,270,597
Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure		375,956,154
Loans Held For Investment Acquired Through Participation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure		3,204,261
Discounted Cash Flow | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure		$ 103,188,783
Discounted Cash Flow | Minimum | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0900
Discounted Cash Flow | Weighted average | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.1199
Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure	399,609,378
Other Liabilities, Fair Value Disclosure	231,885,180
Level 3 | Discounted Cash Flow
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure		$ 379,160,415
Level 3 | Discounted Cash Flow | Mortgage Loan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure		44,947,378
Level 3 | Discounted Cash Flow | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure	395,581,145	375,956,154
Other Liabilities, Fair Value Disclosure		81,134,436
Level 3 | Discounted Cash Flow | Loans Held For Investment Acquired Through Participation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans Receivable, Fair Value Disclosure	4,028,233	$ 3,204,261
Level 3 | Discounted Cash Flow | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure	59,524,887
Level 3 | Discounted Cash Flow | Revolving Credit Facility Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure	35,000,000
Level 3 | Discounted Cash Flow | Mortgage Agreement Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure	44,813,764
Level 3 | Discounted Cash Flow | Repurchase Agreement Payable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other Liabilities, Fair Value Disclosure	$ 92,546,529
Level 3 | Discounted Cash Flow | Minimum | Mortgage Loan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0608
Level 3 | Discounted Cash Flow | Minimum | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0411
Level 3 | Discounted Cash Flow | Maximum | Mortgage Loan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0608
Level 3 | Discounted Cash Flow | Maximum | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0475
Level 3 | Discounted Cash Flow | Maximum | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.1495
Level 3 | Discounted Cash Flow | Weighted average | Mortgage Loan [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0608
Level 3 | Discounted Cash Flow | Weighted average | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input		0.0433
Level 3 | Discounted Cash Flow | Discount Rate | Minimum | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0445	0.0471
Level 3 | Discounted Cash Flow | Discount Rate | Minimum | Loans Held For Investment Acquired Through Participation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1315	0.1190
Level 3 | Discounted Cash Flow | Discount Rate | Minimum | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0986
Level 3 | Discounted Cash Flow | Discount Rate | Minimum | Revolving Credit Facility Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0600
Level 3 | Discounted Cash Flow | Discount Rate | Minimum | Repurchase Agreement Payable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0334
Level 3 | Discounted Cash Flow | Discount Rate | Maximum | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1925	0.1495
Level 3 | Discounted Cash Flow | Discount Rate | Maximum | Loans Held For Investment Acquired Through Participation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1315	0.1190
Level 3 | Discounted Cash Flow | Discount Rate | Maximum | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1925
Level 3 | Discounted Cash Flow | Discount Rate | Maximum | Revolving Credit Facility Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0600
Level 3 | Discounted Cash Flow | Discount Rate | Maximum | Repurchase Agreement Payable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0477
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Loans Held for Investment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1103	0.0977
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Loans Held For Investment Acquired Through Participation
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1315	0.1190
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Obligations Under Participation Agreements
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.1323
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Revolving Credit Facility Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0600
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Mortgage Agreement Payable [Member]
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0608
Level 3 | Discounted Cash Flow | Discount Rate | Weighted average | Repurchase Agreement Payable
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Measurement Input	0.0400