COMMERCIAL MORTGAGE LOANS HELD-FOR-INVESTMENT - Summary of Commercial Mortgage Loans (Details)	9 Months Ended		12 Months Ended
	Sep. 30, 2021 USD ($) mortgage_loan		Dec. 31, 2020 USD ($) mortgage_loan
Accounts, Notes, Loans and Financing Receivable [Line Items]
One Month LIBOR Rate (as a percent)	$ 0.0008		$ 0.0014
Weighted average LIBOR floor rate (as a percent)	0.0083		0.0164
Commercial mortgage loans held-for-investment, at amortized cost	803,074,256	[1]	547,345,334
Commercial real estate portfolio segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unpaid Principal Balance	803,043,750		547,345,334
Carrying Value	$ 803,074,256		$ 547,345,334
Loan Count | mortgage_loan	53		40
Weighted average, floating rate loan, percentage (as a percent)	100.00%		100.00%
Weighted average coupon rate, percentage (as a percent)	4.30%		5.10%
Weighted average, life (in years)	3 years 8 months 12 days		3 years 1 month 6 days
Commercial mortgage loans held-for-investment, at amortized cost	$ 803,074,256		$ 547,345,334
Outstanding senior secured loans from loan participations			15,981,933
Commercial real estate portfolio segment | Hunt CMT
Accounts, Notes, Loans and Financing Receivable [Line Items]
Commercial mortgage loans held-for-investment, at amortized cost	$ 803,074,256		$ 531,363,401

[1] Our consolidated balance sheets include assets and liabilities of consolidated variable interest entities ("VIEs") as the Company was the primary beneficiary of these VIEs. As of September 30, 2021 and December 31, 2020, assets of consolidated VIEs totaled $1,003,113,182 and $591,318,506, respectively and the liabilities of consolidated VIEs totaled $826,707,857 and $463,411,967 respectively. See Note 4 for further discussion.