FAIR VALUE MEASUREMENTS - Information Regarding the Inputs used in Valuing the Servicer Advances (Details)	6 Months Ended
	Jun. 30, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value inputs, monthly servicing fee	1090.00%
Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	0.90%
Mortgage Servicing Amount	0.00174
Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	1.80%
Mortgage Servicing Amount	0.00198
Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Outstanding Servicer Advances to UPB of Underlying Residential Mortgage Loans	1.80%
Mortgage Servicing Amount	0.00198
Prepayment Rate | Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.045
Prepayment Rate | Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.060
Prepayment Rate | Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.059
Delinquency | Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.036
Delinquency | Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.155
Delinquency | Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.152
Discount Rate | Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.052
Discount Rate | Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.057
Discount Rate | Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.052
Collateral Weighted Average Maturity (Years) | Servicer Advances | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	22 years
Collateral Weighted Average Maturity (Years) | Servicer Advances | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	22 years 2 months 12 days
Collateral Weighted Average Maturity (Years) | Servicer Advances | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	22 years