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Fair Value of Financial Instruments - Fair Value Methodology (Details) - Residential whole loans $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | $ 7,684,865 | $ 7,511,210
UPB | 9,018,124 | 9,194,832
Marked to Market Approach |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | 44,300 | 44,900
UPB | 76,300 | 78,200
Level 3 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | 7,632,928 | 7,459,137
Level 3 | Discounted Cash Flow and Liquidation Model |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | 7,588,625 | 7,414,218
Level 3 | Discounted cash flow |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | $ 7,276,067 | $ 7,070,535
Level 3 | Discounted cash flow | Discount rate | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.067 | 0.076
Level 3 | Discounted cash flow | Discount rate | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.057 | 0.062
Level 3 | Discounted cash flow | Discount rate | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.200 | 0.200
Level 3 | Discounted cash flow | Prepayment rate | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.170 | 0.137
Level 3 | Discounted cash flow | Prepayment rate | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0 | 0
Level 3 | Discounted cash flow | Prepayment rate | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.510 | 0.583
Level 3 | Discounted cash flow | Default rate | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.017 | 0.018
Level 3 | Discounted cash flow | Default rate | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0 | 0
Level 3 | Discounted cash flow | Default rate | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.688 | 0.543
Level 3 | Discounted cash flow | Loss severity | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.117 | 0.123
Level 3 | Discounted cash flow | Loss severity | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0 | 0
Level 3 | Discounted cash flow | Loss severity | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 1.000 | 1.000
Level 3 | Liquidation model |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Residential whole loans, fair value | $ 312,558 | $ 343,683
Level 3 | Liquidation model | Discount rate | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.087 | 0.088
Level 3 | Liquidation model | Discount rate | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.080 | 0.080
Level 3 | Liquidation model | Discount rate | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Measurement input | 0.200 | 0.200
Level 3 | Liquidation model | Annual change in home prices | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Annual change in home prices | 2.40% | 3.20%
Level 3 | Liquidation model | Annual change in home prices | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Annual change in home prices | (2.60%) | 0.00%
Level 3 | Liquidation model | Annual change in home prices | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Annual change in home prices | 9.30% | 9.70%
Level 3 | Liquidation model | Liquidation timeline (in years) | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Liquidation timeline (in years) | 1 year 9 months 18 days | 1 year 8 months 12 days
Level 3 | Liquidation model | Liquidation timeline (in years) | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Liquidation timeline (in years) | 9 months 18 days | 1 month 6 days
Level 3 | Liquidation model | Liquidation timeline (in years) | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Liquidation timeline (in years) | 4 years 6 months | 4 years 6 months
Level 3 | Liquidation model | Current value of underlying properties | Weighted Average |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Current value of underlying properties | $ 697 | $ 618
Level 3 | Liquidation model | Current value of underlying properties | Minimum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Current value of underlying properties | 19 | 21
Level 3 | Liquidation model | Current value of underlying properties | Maximum |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Current value of underlying properties | $ 10,000 | $ 8,500

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-3 + Details
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- Definition The fair value as of the balance sheet date of firm holdings in mortgages, mortgage backed securities (investment instruments that represent ownership of an undivided interest in a group of mortgages, where principal and interest from the individual mortgages are used to pay investors' principal and interest on the mortgage backed security) and asset-backed securities that are primarily paid from the cash flows of a discrete pool of receivables or other financial assets (such as credit-card receivables), either fixed or revolving, that by their terms convert into cash within a finite time period. Includes both pledged (to counterparties as collateral for financing transactions) and unpledged holdings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 940 -SubTopic 320 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479035/940-320-45-2 + Details
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