FAIR VALUE MEASUREMENTS - Schedule of Inputs Used In Valuing Residential Mortgage Loans, Consumer Loans, Mortgage Loans Receivable, Derivatives, and Mortgage Backed Securities (Details) $ in Thousands	Sep. 30, 2023 USD ($) security
Residential Mortgage Loans, Held-for-Investment, at Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, fair value	$ 370,957
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	0.087
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	0.036
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	0.069
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	0.211
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	0.092
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	0.050
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	0.170
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	0.610
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	0.089
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	0.044
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	0.093
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	0.412
Consumer Loans Held-for-Investment, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	$ 1,436,080
Consumer Loans Held-for-Investment, At Fair Value | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	303,881
Consumer Loans Held-for-Investment, At Fair Value | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	$ 1,132,199
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Discount Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.084
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Prepayment Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.091
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Delinquency | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.017
Consumer Loans Held-for-Investment, At Fair Value | Minimum | Loss Severity | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.600
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Discount Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.094
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Prepayment Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.366
Consumer Loans Held-for-Investment, At Fair Value | Maximum | Delinquency | SpringCastle
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 | Maximum | Loss Severity | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.600
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Discount Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.086
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Discount Rate | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.111
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Prepayment Rate | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.177
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Prepayment Rate | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.205
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Delinquency | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.047
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Delinquency | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.053
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Loss Severity | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.600
Consumer Loans Held-for-Investment, At Fair Value | Weighted Average | Loss Severity | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.070
Interest rate lock commitments
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, fair value	$ 6,498
Interest rate lock commitments | Minimum | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.003
Interest rate lock commitments | Minimum | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.00007
Interest rate lock commitments | Maximum | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	1.000
Interest rate lock commitments | Maximum | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.03450
Interest rate lock commitments | Weighted Average | Loan Funding Probability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.826
Interest rate lock commitments | Weighted Average | Fair Value of Initial Servicing Rights (Bps)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.02224
Mortgage-Backed Securities Issued
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, fair value	$ 245,695
Mortgage-Backed Securities Issued | Discount Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.064
Mortgage-Backed Securities Issued | Prepayment Rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.177
Mortgage-Backed Securities Issued | Delinquency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.047
Mortgage-Backed Securities Issued | Loss Severity
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Securities, measurement input	0.935
Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value | Minimum | Dealer price quotes and historical sale transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input | security	0.492
Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value | Maximum | Dealer price quotes and historical sale transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input | security	1.000
Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value | Weighted Average | Dealer price quotes and historical sale transactions
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held for sale, measurement input | security	0.879
Performing loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 109,519
Performing loans | Acquired loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 43,697
Performing loans | Acquired loans | 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	0.087
Performing loans | Acquired loans | 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	0.019
Performing loans | Acquired loans | 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	0.023
Performing loans | Acquired loans | 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	0.121
Performing loans | Acquired loans | 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	0.092
Performing loans | Acquired loans | 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	0.077
Performing loans | Acquired loans | 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	0.100
Performing loans | Acquired loans | 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	0.610
Performing loans | Acquired loans | 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	0.090
Performing loans | Acquired loans | 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	0.054
Performing loans | Acquired loans | 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	0.054
Performing loans | Acquired loans | 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	0.213
Performing loans | Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 65,822
Performing loans | Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Percentage of loans	47.90%
Performing loans | Originated loans | 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	0.060
Performing loans | Originated loans | 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	0.010
Performing loans | Originated loans | 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	0.001
Performing loans | Originated loans | 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	0.001
Performing loans | Originated loans | 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	0.421
Performing loans | Originated loans | 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	0.414
Performing loans | Originated loans | 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	0.633
Performing loans | Originated loans | 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	0.053
Performing loans | Originated loans | 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	0.030
Performing loans | Originated loans | 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	0.125
Non-performing loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 29,834
Non-performing loans | Acquired loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 19,807
Non-performing loans | Acquired loans | 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	0.086
Non-performing loans | Acquired loans | 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	0.061
Non-performing loans | Acquired loans | 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	2.0
Non-performing loans | Acquired loans | 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	2.271
Non-performing loans | Acquired loans | 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	0.091
Non-performing loans | Acquired loans | 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	0.127
Non-performing loans | Acquired loans | 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	6.4
Non-performing loans | Acquired loans | 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	7.825
Non-performing loans | Acquired loans | 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	0.089
Non-performing loans | Acquired loans | 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	0.081
Non-performing loans | Acquired loans | 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	2.9
Non-performing loans | Acquired loans | 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	2.799
Non-performing loans | Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 10,027
Non-performing loans | Originated loans | Residential Mortgage Loans Held-for-Sale, At Fair Value | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Percentage of loans	76.90%
Non-performing loans | Originated loans | 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	0.060
Non-performing loans | Originated loans | 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	0.5
Non-performing loans | Originated loans | 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	9.2
Non-performing loans | Originated loans | 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	1.9