FAIR VALUE MEASUREMENTS - Weighted Average Inputs used in Valuing Excess MSRs Owned Directly and through Equity Method Investees (Details)	12 Months Ended
	Dec. 31, 2022 $ / Loan	Dec. 31, 2021 $ / Loan
Prepayment Rate | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.013	0.053
Prepayment Rate | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.978	0.504
Prepayment Rate | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.092	0.102
Prepayment Rate | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.026	0.06
Prepayment Rate | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.978	0.146
Prepayment Rate | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.080	0.102
Prepayment Rate | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.013	0.067
Prepayment Rate | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.932	0.504
Prepayment Rate | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.150	0.067
Prepayment Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.028	0.053
Prepayment Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.812	0.143
Prepayment Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.103	0.126
Prepayment Rate | Directly Held | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.028	0.036
Prepayment Rate | Directly Held | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.135	0.124
Prepayment Rate | Directly Held | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.073	0.068
Prepayment Rate | Held through Equity Method Investees | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.084	0.054
Prepayment Rate | Held through Equity Method Investees | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.110	0.085
Prepayment Rate | Held through Equity Method Investees | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.094	0.067
Delinquency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.001	0.001
Delinquency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.800	0.646
Delinquency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.053	0.031
Delinquency | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.001	0.001
Delinquency | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.667	0.022
Delinquency | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.020	0.009
Delinquency | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.010	0.007
Delinquency | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.750	0.646
Delinquency | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.211	0.118
Delinquency | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.002	0.014
Delinquency | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.800	0.063
Delinquency | Ginnie Mae | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.089	0.041
Delinquency | Directly Held | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.002	0.001
Delinquency | Directly Held | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.101	0.096
Delinquency | Directly Held | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.036	0.032
Delinquency | Held through Equity Method Investees | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.029	0.003
Delinquency | Held through Equity Method Investees | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.054	0.016
Delinquency | Held through Equity Method Investees | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.039	0.009
Recapture Rate | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0
Recapture Rate | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.314
Recapture Rate | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.10
Recapture Rate | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0
Recapture Rate | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.314
Recapture Rate | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.107
Recapture Rate | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.04
Recapture Rate | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.27
Recapture Rate | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.068
Recapture Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.048
Recapture Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.245
Recapture Rate | Ginnie Mae | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		0.127
Recapture Rate | Directly Held | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0	0
Recapture Rate | Directly Held | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.914	0.252
Recapture Rate | Directly Held | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.554	0.073
Recapture Rate | Held through Equity Method Investees | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.454	0.03
Recapture Rate | Held through Equity Method Investees | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.640	0.095
Recapture Rate | Held through Equity Method Investees | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.587	0.057
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0002	0.0025
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0216	0.0086
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0034	0.0033
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0007	0.0025
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0104	0.0030
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0030	0.0028
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0002	0.0026
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0216	0.0086
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0046	0.0048
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0011	0.0031
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0086	0.0045
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Ginnie Mae | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0041	0.0039
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Directly Held | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0006	0.0006
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Directly Held | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0031	0.0032
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Directly Held | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0019	0.0019
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Held through Equity Method Investees | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0015	0.0015
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Held through Equity Method Investees | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0026	0.0026
Mortgage Servicing Amount or Excess Mortgage Servicing Amount | Held through Equity Method Investees | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	0.0021	0.0022
Collateral Weighted Average Maturity (Years) | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	0 years	0 years
Collateral Weighted Average Maturity (Years) | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	39 years	40 years
Collateral Weighted Average Maturity (Years) | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	24 years	24 years
Collateral Weighted Average Maturity (Years) | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	0 years	0 years
Collateral Weighted Average Maturity (Years) | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	39 years	40 years
Collateral Weighted Average Maturity (Years) | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	23 years	23 years
Collateral Weighted Average Maturity (Years) | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	0 years	0 years
Collateral Weighted Average Maturity (Years) | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	36 years	30 years
Collateral Weighted Average Maturity (Years) | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	24 years	24 years
Collateral Weighted Average Maturity (Years) | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	0 years	0 years
Collateral Weighted Average Maturity (Years) | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	39 years	30 years
Collateral Weighted Average Maturity (Years) | Ginnie Mae | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	27 years	28 years
Collateral Weighted Average Maturity (Years) | Directly Held | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	11 years	11 years
Collateral Weighted Average Maturity (Years) | Directly Held | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	29 years	28 years
Collateral Weighted Average Maturity (Years) | Directly Held | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	21 years	21 years
Collateral Weighted Average Maturity (Years) | Held through Equity Method Investees | Excess MSRs | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	15 years	16 years
Collateral Weighted Average Maturity (Years) | Held through Equity Method Investees | Excess MSRs | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	22 years	23 years
Collateral Weighted Average Maturity (Years) | Held through Equity Method Investees | Excess MSRs | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Collateral Weighted Average Maturity (Years)	19 years	19 years
Measurement Input, Servicing Cost | Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	6.80	6.40
Measurement Input, Servicing Cost | Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	7.00	7.20
Measurement Input, Servicing Cost | Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	6.90	7.00
Measurement Input, Servicing Cost | Non-Agency | MSRs And MSR Financing Receivables
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input		10.70
Measurement Input, Servicing Cost | Non-Agency | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	7.30	10.60
Measurement Input, Servicing Cost | Non-Agency | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	17.20	15.80
Measurement Input, Servicing Cost | Non-Agency | MSRs And MSR Financing Receivables | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	8.70
Measurement Input, Servicing Cost | Ginnie Mae | MSRs And MSR Financing Receivables
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	8.30	8.80
Measurement Input, Servicing Cost | Ginnie Mae | MSRs And MSR Financing Receivables | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	8.30	8.80
Measurement Input, Servicing Cost | Ginnie Mae | MSRs And MSR Financing Receivables | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Servicing asset, measurement input	8.40	8.90