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Summary of Significant Accounting Policies - Residential Whole Loans (Details) - USD ($) $ in Thousands | 9 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 | Dec. 31, 2023
Accounting Policies [Abstract] |  |  |
LTV ratio (as a percent) |  | 80.00% |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Total Residential whole loans | [1],[2] | $ 9,027,371 | $ 9,041,292
Residential whole loan |  |  |
Accounting Policies [Abstract] |  |  |
LTV ratio (as a percent) |  | 64.00% |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Total Residential whole loans |  | $ 9,027,371 | $ 9,041,292
Residential whole loan | Business purpose loans |  |  |
Accounting Policies [Abstract] |  |  |
LTV ratio (as a percent) |  | 68.00% | 67.00%
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Total Residential whole loans |  | $ 3,682,499 | $ 3,989,351
Residential whole loan | Business purpose loans | Multifamily Properties |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Threshold balance (below) |  | $ 10,000 |
Residential Whole Loan, Unsettled Purchases |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |
Total Residential whole loans |  |  | $ 103,700
[1] | Includes approximately $6.3 billion and $5.7 billion of Residential whole loans transferred to consolidated variable interest entities (“VIEs”) at September 30, 2024 and December 31, 2023, respectively. Such assets can be used only to settle the obligations of each respective VIE.
[2] | See Note 6 for information regarding the Company’s pledged assets.

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