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VARIABLE INTEREST ENTITIES - Narrative (Details) $ in Thousands		3 Months Ended			9 Months Ended	12 Months Ended
	Jan. 28, 2021 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Mar. 31, 2022 USD ($)	Sep. 30, 2023 USD ($) loan	Dec. 31, 2022 USD ($) loan	Jan. 11, 2019 USD ($)	Mar. 30, 2017 USD ($)
Variable Interest Entity [Line Items]
Receivables related to repayments of outstanding principal on previous mortgage assets		$ 99,400			$ 99,400	$ 127,600
Loans held for investment		2,180,412			2,180,412	$ 2,264,008
Sale of common stock			$ 103,393	$ 2,874
Credit risk, financial instrument, maximum exposure					238,200
ACRE Commercial Mortgage 2021-FL4 Ltd. and ACRE Commercial Mortgage 2021-FL4 LLC \| Preferred Stock
Variable Interest Entity [Line Items]
Sale of common stock	$ 64,300
ACRE Commercial Mortgage 2021-FL4 Ltd. and ACRE Commercial Mortgage 2021-FL4 LLC \| Preferred Stock \| Wholly Owned Subsidiary To Parent Company
Variable Interest Entity [Line Items]
Sale of common stock					64,300
Variable Interest Entity, Not Primary Beneficiary \| NY \| Residential Condominium
Variable Interest Entity [Line Items]
Credit risk, financial instrument, maximum exposure					$ 84,600
Floating Rate Notes, Weighted Average Coupon Rate, LIBOR Plus 1.85%
Variable Interest Entity [Line Items]
Number of properties collateralized for mortgage loan \| loan					14	16
Receivables related to repayments of outstanding principal		457,600			$ 457,600	$ 429,400
Mortgaged Assets \| Holdco
Variable Interest Entity [Line Items]
Principal amount of certificates retained by wholly owned subsidiary of the entity		58,500			58,500
Offered Certificates \| Parent Company
Variable Interest Entity [Line Items]
Preferred equity fully funded amount		52,900			52,900
Secured funding agreements \| Parent Company
Variable Interest Entity [Line Items]
Loans held for investment		111,400			111,400
Secured, Floating Rate Notes \| ACRE Commercial Mortgage 2021-FL4 Ltd. and ACRE Commercial Mortgage 2021-FL4 LLC
Variable Interest Entity [Line Items]
Aggregate principal amount	$ 603,000
Secured, Floating Rate Notes \| ACRE Commercial Mortgage 2021-FL4 Ltd. and ACRE Commercial Mortgage 2021-FL4 LLC \| Wholly Owned Subsidiary To Parent Company
Variable Interest Entity [Line Items]
Aggregate principal amount		62,500			62,500
Collateral amount		126,800			126,800
Repayments of debt		155			$ 43,000
FL4 Mortgage Assets
Variable Interest Entity [Line Items]
Number of properties collateralized for mortgage loan \| loan					11	12
Receivables related to repayments of outstanding principal		$ 417,100			$ 417,100	$ 458,300
Receivables related to repayments of outstanding principal on mortgage assets						$ 1,900
Wells Fargo Facility \| Notes Payable
Variable Interest Entity [Line Items]
Debt commitment								$ 308,800
Wells Fargo Facility \| Notes Payable \| 2019 FL3 CLO Securitization
Variable Interest Entity [Line Items]
Debt commitment							$ 504,100
Wells Fargo Facility \| Collateralized Loan Obligations
Variable Interest Entity [Line Items]
Debt commitment								$ 32,400
Wells Fargo Facility \| Collateralized Loan Obligations \| 2019 FL3 CLO Securitization
Variable Interest Entity [Line Items]
Debt commitment							$ 52,900