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Summary of Significant Accounting Policies - Residential Whole Loans (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2025 | Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
LTV ratio (as a percent) | 80.00% |
Residential whole loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
LTV ratio (as a percent) | 64.00% | 64.00%
Residential whole loans | Business purpose loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
LTV ratio (as a percent) | 67.00% | 67.00%
Residential whole loans | Business purpose loans | Multifamily Properties |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Threshold balance (below) | $ 10 |

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Balance Type: | debit
Period Type: | instant

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- Definition The LTV of which the Company has assessed its residential whole loans at carrying value will have a higher likelihood of default than newly originated mortgage loans + References No definition available. + Details
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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/2009/role/commonPracticeRef -Topic 310 -SubTopic 20 -Name Accounting Standards Codification -Section 40 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481628/310-20-40-7 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481990/310-10-45-2 + Details
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- Details
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- Details
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- Details
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