FAIR VALUE MEASUREMENTS - Information Regarding the Inputs used in Valuing the Servicer Advances (Details)	9 Months Ended
	Sep. 30, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value inputs, monthly servicing fee	0.027%
Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	1.10%
Mortgage Servicing Amount	0.00182
Servicer Advances | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.026
Servicer Advances | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.033
Servicer Advances | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.062
Servicer Advances | Minimum | Collateral Weighted Average Maturity (Years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	21 years 2 months 12 days
Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	2.20%
Mortgage Servicing Amount	0.00199
Servicer Advances | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.044
Servicer Advances | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.205
Servicer Advances | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.067
Servicer Advances | Maximum | Collateral Weighted Average Maturity (Years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	21 years 10 months 24 days
Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	2.20%
Mortgage Servicing Amount	0.00198
Servicer Advances | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.044
Servicer Advances | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.201
Servicer Advances | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.062
Servicer Advances | Weighted Average | Collateral Weighted Average Maturity (Years)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	21 years 10 months 24 days