FAIR VALUE MEASUREMENT - Schedule of Inputs Used In Valuing Residential Mortgage Loans, Consumer Loans, Derivatives, and Mortgage Backed Securities (Details) $ in Thousands	Mar. 31, 2021 USD ($)
Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 1,744,924
Residential Mortgage Loans, Held-for-Investment, at Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, fair value	$ 656,752
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.058
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.020
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.014
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.300
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.080
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.064
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.029
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.609
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.060
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.060
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.015
Residential Mortgage Loans, Held-for-Investment, at Fair Value | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for investment, measurement input	0.581
Consumer Loans Held-for-Investment, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	$ 638,986
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.075
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.204
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.048
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.788
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.097
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.341
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.236
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.924
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.075
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.204
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.048
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.788
IRLCs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, fair value	$ 54,092
IRLCs | Minimum | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.000
IRLCs | Minimum | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.040
IRLCs | Maximum | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	1.000
IRLCs | Maximum | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	283.4
IRLCs | Weighted Average | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.832
IRLCs | Weighted Average | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	102.8
Mortgage-Backed Securities Issued
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, fair value	$ 1,260,557
Mortgage-Backed Securities Issued | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.016
Mortgage-Backed Securities Issued | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.036
Mortgage-Backed Securities Issued | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.010
Mortgage-Backed Securities Issued | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.200
Mortgage-Backed Securities Issued | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.049
Mortgage-Backed Securities Issued | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.300
Mortgage-Backed Securities Issued | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.048
Mortgage-Backed Securities Issued | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.900
Mortgage-Backed Securities Issued | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.032
Mortgage-Backed Securities Issued | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.125
Mortgage-Backed Securities Issued | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.035
Mortgage-Backed Securities Issued | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.632
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 1,731,794
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.030
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.020
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.075
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.250
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.031
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.500
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Weighted Average | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.041
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Weighted Average | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.155
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Weighted Average | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.013
Non-Purchased Credit Deteriorated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Weighted Average | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.150
Originated | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 13,130
Originated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.043
Originated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.055
Originated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.030
Originated | Residential Mortgage Loans Held-for-Sale, At Fair Value | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input	0.500