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Residential Whole Loans - Additional Credit Related Information (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2023 | Jun. 30, 2023 | Mar. 31, 2023 | Sep. 30, 2022 | Jun. 30, 2022 | Mar. 31, 2022 | Sep. 30, 2023 | Dec. 31, 2022
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | $ 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 59,041 |  |  |  |  |  | 59,041 |
2020 | 208,981 |  |  |  |  |  | 208,981 |
2019 | 545,088 |  |  |  |  |  | 545,088 |
Prior | 793,094 |  |  |  |  |  | 793,094 |
Total | 1,606,204 |  |  |  |  |  | 1,606,204 |
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 14 |
Gross write-offs, 2020 |  |  |  |  |  |  | 189 |
Gross write-offs, 2019 |  |  |  |  |  |  | 3,609 |
Gross write-offs, prior |  |  |  |  |  |  | 2,273 |
Gross write-offs | 1,226 | $ 2,292 | $ 2,567 | $ 282 | $ 360 | $ 523 | $ 6,085 |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 80.00% |
Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 57,645 |  |  |  |  |  | 57,645 |
2020 | 197,511 |  |  |  |  |  | 197,511 |
2019 | 536,827 |  |  |  |  |  | 536,827 |
Prior | 720,221 |  |  |  |  |  | 720,221 |
Total | 1,512,204 |  |  |  |  |  | 1,512,204 |
Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 1,396 |  |  |  |  |  | 1,396 |
2020 | 11,470 |  |  |  |  |  | 11,470 |
2019 | 8,261 |  |  |  |  |  | 8,261 |
Prior | 72,873 |  |  |  |  |  | 72,873 |
Total | 94,000 |  |  |  |  |  | 94,000 |
Non-QM loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 46,281 |  |  |  |  |  | 46,281 |
2020 | 183,766 |  |  |  |  |  | 183,766 |
2019 | 412,022 |  |  |  |  |  | 412,022 |
Prior | 231,722 |  |  |  |  |  | 231,722 |
Total | 873,791 |  |  |  |  |  | 873,791 |
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 0 |
Gross write-offs, 2020 |  |  |  |  |  |  | 71 |
Gross write-offs, 2019 |  |  |  |  |  |  | 25 |
Gross write-offs, prior |  |  |  |  |  |  | 110 |
Gross write-offs |  |  |  |  |  |  | $ 206 |
Non-QM loans | Settled Whole Loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 65.00% | 65.00%
Non-QM loans | Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 44,885 |  |  |  |  |  | 44,885 |
2020 | 172,296 |  |  |  |  |  | 172,296 |
2019 | 407,541 |  |  |  |  |  | 407,541 |
Prior | 226,678 |  |  |  |  |  | 226,678 |
Total | 851,400 |  |  |  |  |  | 851,400 |
Non-QM loans | Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 1,396 |  |  |  |  |  | 1,396 |
2020 | 11,470 |  |  |  |  |  | 11,470 |
2019 | 4,481 |  |  |  |  |  | 4,481 |
Prior | 5,044 |  |  |  |  |  | 5,044 |
Total | 22,391 |  |  |  |  |  | 22,391 |
Transitional loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 504 |  |  |  |  |  | 504 |
2020 | 3,915 |  |  |  |  |  | 3,915 |
2019 | 25,745 |  |  |  |  |  | 25,745 |
Prior | 7,782 |  |  |  |  |  | 7,782 |
Total | 37,946 |  |  |  |  |  | 37,946 |
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 14 |
Gross write-offs, 2020 |  |  |  |  |  |  | 47 |
Gross write-offs, 2019 |  |  |  |  |  |  | 2,970 |
Gross write-offs, prior |  |  |  |  |  |  | 1,639 |
Gross write-offs |  |  |  |  |  |  | $ 4,670 |
Transitional loans | Settled Whole Loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 64.00% | 66.00%
Transitional loans | Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 504 |  |  |  |  |  | 504 |
2020 | 3,915 |  |  |  |  |  | 3,915 |
2019 | 23,565 |  |  |  |  |  | 23,565 |
Prior | 7,782 |  |  |  |  |  | 7,782 |
Total | 35,766 |  |  |  |  |  | 35,766 |
Transitional loans | Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 2,180 |  |  |  |  |  | 2,180 |
Prior | 0 |  |  |  |  |  | 0 |
Total | 2,180 |  |  |  |  |  | 2,180 |
Single-family rental loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 12,256 |  |  |  |  |  | 12,256 |
2020 | 21,300 |  |  |  |  |  | 21,300 |
2019 | 107,321 |  |  |  |  |  | 107,321 |
Prior | 42,002 |  |  |  |  |  | 42,002 |
Total | 182,879 |  |  |  |  |  | 182,879 |
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 0 |
Gross write-offs, 2020 |  |  |  |  |  |  | 71 |
Gross write-offs, 2019 |  |  |  |  |  |  | 614 |
Gross write-offs, prior |  |  |  |  |  |  | 0 |
Gross write-offs |  |  |  |  |  |  | $ 685 |
Single-family rental loans | Settled Whole Loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 68.00% | 69.00%
Single-family rental loans | Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 12,256 |  |  |  |  |  | 12,256 |
2020 | 21,300 |  |  |  |  |  | 21,300 |
2019 | 105,721 |  |  |  |  |  | 105,721 |
Prior | 41,917 |  |  |  |  |  | 41,917 |
Total | 181,194 |  |  |  |  |  | 181,194 |
Single-family rental loans | Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 1,600 |  |  |  |  |  | 1,600 |
Prior | 85 |  |  |  |  |  | 85 |
Total | 1,685 |  |  |  |  |  | 1,685 |
Seasoned performing loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 72,675 |  |  |  |  |  | 72,675 |
Total | 72,675 |  |  |  |  |  | 72,675 |
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 0 |
Gross write-offs, 2020 |  |  |  |  |  |  | 0 |
Gross write-offs, 2019 |  |  |  |  |  |  | 0 |
Gross write-offs, prior |  |  |  |  |  |  | 0 |
Gross write-offs |  |  |  |  |  |  | $ 0 |
Seasoned performing loans | Settled Whole Loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 28.00% | 30.00%
Seasoned performing loans | Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | $ 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 70,272 |  |  |  |  |  | 70,272 |
Total | 70,272 |  |  |  |  |  | 70,272 |
Seasoned performing loans | Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 2,403 |  |  |  |  |  | 2,403 |
Total | 2,403 |  |  |  |  |  | 2,403 |
Purchased credit deteriorated loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 438,913 |  |  |  |  |  | 438,913 |
Total | 438,913 |  |  |  |  |  | 438,913 | $ 470,294
Gross write-offs, 2023 |  |  |  |  |  |  | 0 |
Gross write-offs, 2022 |  |  |  |  |  |  | 0 |
Gross write-offs, 2021 |  |  |  |  |  |  | 0 |
Gross write-offs, 2020 |  |  |  |  |  |  | 0 |
Gross write-offs, 2019 |  |  |  |  |  |  | 0 |
Gross write-offs, prior |  |  |  |  |  |  | 524 |
Gross write-offs |  |  |  |  |  |  | 524 |
Purchased credit deteriorated loans | Debt-to-Value Ratio, Less Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 373,572 |  |  |  |  |  | 373,572 |
Total | 373,572 |  |  |  |  |  | 373,572 |
Purchased credit deteriorated loans | Debt-to-Value Ratio, Greater Than 80 Percent |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
2023 | 0 |  |  |  |  |  | 0 |
2022 | 0 |  |  |  |  |  | 0 |
2021 | 0 |  |  |  |  |  | 0 |
2020 | 0 |  |  |  |  |  | 0 |
2019 | 0 |  |  |  |  |  | 0 |
Prior | 65,341 |  |  |  |  |  | 65,341 |
Total | 65,341 |  |  |  |  |  | 65,341 |
Certain rehabilitation loans | Transitional loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Purchased performing loans | $ 423,600 |  |  |  |  |  | $ 423,600 | $ 223,200
Certain rehabilitation loans | Settled Whole Loans |  |  |  |  |  |  |  |
Financing Receivable, Credit Quality Indicator [Line Items] |  |  |  |  |  |  |  |
Ratio loan- to-value (as a percent) |  |  |  |  |  |  | 69.00% | 70.00%

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