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, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Financing liability	$ 41,800
Residential mortgage loans, HFI, at fair value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, fair value	$ 334,589	$ 361,890
Residential mortgage loans, HFI, at fair value | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.066	0.079
Residential mortgage loans, HFI, at fair value | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.096	0.093
Residential mortgage loans, HFI, at fair value | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.077	0.084
Residential mortgage loans, HFI, at fair value | Prepayment Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.056	0.054
Residential mortgage loans, HFI, at fair value | Prepayment Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.076	0.082
Residential mortgage loans, HFI, at fair value | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.074	0.080
Residential mortgage loans, HFI, at fair value | CDR | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.009	0.013
Residential mortgage loans, HFI, at fair value | CDR | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.036	0.049
Residential mortgage loans, HFI, at fair value | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.017	0.033
Residential mortgage loans, HFI, at fair value | Loss Severity | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.260	0.124
Residential mortgage loans, HFI, at fair value | Loss Severity | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.485	0.337
Residential mortgage loans, HFI, at fair value | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans, held-for-investment, measurement input	0.390	0.264
Consumer Loans HFI, at Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	$ 598,147	$ 665,565
Consumer Loans HFI, at Fair Value | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	178,365	219,308
Consumer Loans HFI, at Fair Value | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	213,007	$ 446,257
Consumer Loans HFI, at Fair Value | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans	$ 206,775
Consumer Loans HFI, at Fair Value | Discount Rate | Minimum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.092	0.092
Consumer Loans HFI, at Fair Value | Discount Rate | Minimum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.075	0.079
Consumer Loans HFI, at Fair Value | Discount Rate | Minimum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.067
Consumer Loans HFI, at Fair Value | Discount Rate | Maximum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.102	0.102
Consumer Loans HFI, at Fair Value | Discount Rate | Maximum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.175	0.179
Consumer Loans HFI, at Fair Value | Discount Rate | Maximum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.229
Consumer Loans HFI, at Fair Value | Discount Rate | Weighted Average | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.094	0.094
Consumer Loans HFI, at Fair Value | Discount Rate | Weighted Average | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.117	0.101
Consumer Loans HFI, at Fair Value | Discount Rate | Weighted Average | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.077
Consumer Loans HFI, at Fair Value | Prepayment Rate | Minimum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.123	0.129
Consumer Loans HFI, at Fair Value | Prepayment Rate | Minimum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.000	0.000
Consumer Loans HFI, at Fair Value | Prepayment Rate | Minimum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.026
Consumer Loans HFI, at Fair Value | Prepayment Rate | Maximum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.391	0.384
Consumer Loans HFI, at Fair Value | Prepayment Rate | Maximum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.220	0.231
Consumer Loans HFI, at Fair Value | Prepayment Rate | Maximum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.343
Consumer Loans HFI, at Fair Value | Prepayment Rate | Weighted Average | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.137	0.145
Consumer Loans HFI, at Fair Value | Prepayment Rate | Weighted Average | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.127	0.178
Consumer Loans HFI, at Fair Value | Prepayment Rate | Weighted Average | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.172
Consumer Loans HFI, at Fair Value | CDR | Minimum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.030	0.023
Consumer Loans HFI, at Fair Value | CDR | Minimum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.030	0.040
Consumer Loans HFI, at Fair Value | CDR | Minimum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.009
Consumer Loans HFI, at Fair Value | CDR | Maximum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.366	0.171
Consumer Loans HFI, at Fair Value | CDR | Maximum | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.620	0.500
Consumer Loans HFI, at Fair Value | CDR | Maximum | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.077
Consumer Loans HFI, at Fair Value | CDR | Weighted Average | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.054	0.051
Consumer Loans HFI, at Fair Value | CDR | Weighted Average | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.275	0.143
Consumer Loans HFI, at Fair Value | CDR | Weighted Average | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.033
Consumer Loans HFI, at Fair Value | Loss Severity | Minimum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.804	0.742
Consumer Loans HFI, at Fair Value | Loss Severity | Maximum | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	1.000	1.000
Consumer Loans HFI, at Fair Value | Loss Severity | Weighted Average | SpringCastle
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.932	0.923
Consumer Loans HFI, at Fair Value | Loss Severity | Weighted Average | Marcus
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.875	0.875
Consumer Loans HFI, at Fair Value | Loss Severity | Weighted Average | Upgrade
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Consumer loans, held-for-investment, measurement input	0.900
IRLCs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, fair value	$ 20,564	$ 11,294
IRLCs | Loan Funding Probability | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.021	0.000
IRLCs | Loan Funding Probability | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	1.000	1.000
IRLCs | Loan Funding Probability | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.817	0.861
IRLCs | Fair Value of Initial Servicing Rights (bps) | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.00034	0.00010
IRLCs | Fair Value of Initial Servicing Rights (bps) | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.04086	0.04267
IRLCs | Fair Value of Initial Servicing Rights (bps) | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Derivative, measurement input	0.02712	0.02818
Asset-Backed Securities Issued
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset-backed securities, fair value	$ 153,019	$ 185,460
Asset-Backed Securities Issued | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset-backed securities, measurement input	0.050	0.054
Asset-Backed Securities Issued | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset-backed securities, measurement input	0.138	0.145
Asset-Backed Securities Issued | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset-backed securities, measurement input	0.054	0.051
Asset-Backed Securities Issued | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Asset-backed securities, measurement input	0.932	0.923
Performing Financial Instruments | RTLs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held For investment, fair value	$ 2,483,692	$ 2,128,801
Performing Financial Instruments | RTLs | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.082	0.083
Performing Financial Instruments | RTLs | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.087	0.099
Performing Financial Instruments | RTLs | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.082	0.083
Performing Financial Instruments | RTLs | Prepayment Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.000	0.000
Performing Financial Instruments | RTLs | Prepayment Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.500	0.500
Performing Financial Instruments | RTLs | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.463	0.458
Performing Financial Instruments | RTLs | CDR | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.000	0.005
Performing Financial Instruments | RTLs | CDR | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.018	0.018
Performing Financial Instruments | RTLs | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.005	0.005
Performing Financial Instruments | RTLs | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.250	0.250
Performing Financial Instruments | RTL Investments Of Consolidated Entities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held For investment, fair value	$ 297,074
Performing Financial Instruments | RTL Investments Of Consolidated Entities | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.083
Performing Financial Instruments | RTL Investments Of Consolidated Entities | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.500
Performing Financial Instruments | RTL Investments Of Consolidated Entities | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.005
Performing Financial Instruments | RTL Investments Of Consolidated Entities | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.250
Performing Financial Instruments | RTL Financing Liability
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held For investment, fair value	$ 45,903
Performing Financial Instruments | RTL Financing Liability | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.082
Performing Financial Instruments | RTL Financing Liability | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.500
Performing Financial Instruments | RTL Financing Liability | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.005
Performing Financial Instruments | RTL Financing Liability | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held-for-investment, measurement input	0.250
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 17,487	$ 17,700
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.066	0.070
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.083	0.086
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.071	0.079
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Prepayment Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.044	0.060
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Prepayment Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.076	0.082
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Prepayment Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.070	0.079
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.009	0.018
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.036	0.050
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.021	0.031
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Loss Severity | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.286	0.206
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Loss Severity | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.485	0.337
Performing Financial Instruments | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Loss Severity | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.350	0.240
Non-performing loans | RTLs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Mortgage loans, held For investment, fair value	$ 100,400	$ 55,200
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, fair value	$ 8,050	$ 9,466
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.096	0.085
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.122	0.093
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Discount Rate | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.113	0.088
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.036	0.013
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.057	0.051
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | CDR | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.050	0.038
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Annual Change in Home Prices | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.007	0.086
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Annual Change in Home Prices | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.043	0.158
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Annual Change in Home Prices | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	0.031	0.109
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Current Value of Underlying Properties | Minimum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	2.800	2.649
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Current Value of Underlying Properties | Maximum
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	3.164	3.103
Non-performing loans | Acquired loans | Residential Mortgage Loans HFS, at Fair Value | Current Value of Underlying Properties | Weighted Average
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans held-for-sale, measurement input	2.923	2.795