SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Jun. 30, 2020	Dec. 31, 2020	Feb. 14, 2019	Jan. 15, 2019	Dec. 15, 2015
Debt and Equity Securities, FV-NI [Line Items]
Non-accrual status	$ 0
Recognized impairment	0
Allowance for loan losses	0
Principal amount	40,250,000		$ 40,250,000
Deferred financing costs amortized	$ 1,017,419
Common stock, shares authorized (in shares)	450,000,000		450,000,000
Common stock, par value (in dollars per share)	$ 0.01		$ 0.01
Common stock, shares issued (in shares)	24,943,383		24,943,383
Common stock, shares outstanding (in shares)	24,943,383		24,943,383
Stock repurchase program, authorized amount						$ 10,000,000
Other Operating Income (Expense)
Debt and Equity Securities, FV-NI [Line Items]
Reclassification of deferred financing costs from other assets to other operating expenses		$ 624,816
Redeemable Preferred Stock
Debt and Equity Securities, FV-NI [Line Items]
Preferred stock, shares outstanding (in shares)	0		0
Preferred stock, shares authorized (in shares)	50,000,000		50,000,000
Preferred stock, par value (in dollars per share)	$ 0.01		$ 0.01
Preferred stock, shares issued (in shares)	0		0
Delayed Draw Facility | Credit Agreement
Debt and Equity Securities, FV-NI [Line Items]
Principal amount	$ 40,250,000			$ 40,250,000	$ 40,250,000
Collateralized Loan Obligations
Debt and Equity Securities, FV-NI [Line Items]
Maximum exposure to loss from consolidated trusts	$ 124,046,671		$ 124,046,671