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Use of Special Purpose Entities and Variable Interest Entities (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2021 | Sep. 30, 2021 | Dec. 31, 2020
Variable Interest Entity [Line Items] |  |  |
Total residential whole loans | $ 7,100,000 | $ 7,100,000 | $ 5,300,000
Asset-backed Securities, Securitized Loans and Receivables |  |  |
Variable Interest Entity [Line Items] |  |  |
Proceeds from issuance of debt |  | 2,788,354 | 1,853,408
Residential whole loans | 2,300,000 | 2,300,000 | 1,800,000
Securitized debt | 2,000,000 | 2,000,000 | 1,500,000
Asset-backed Securities, Securitized Loans and Receivables | Other Assets |  |  |
Variable Interest Entity [Line Items] |  |  |
Real estate owned at fair value | 36,100 | 36,100 | $ 49,500
Senior Bonds |  |  |
Variable Interest Entity [Line Items] |  |  |
Proceeds from issuance of debt | 277,300 | 1,500,000 |
Proceed from debt net of offering expenses and underwriting discount | $ 277,300 | $ 1,500,000 |

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- Definition Loans, Including Fair Value Loans, Credit Impaired Loans and Other Loans at Carrying Value + References No definition available. + Details
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- Definition The cash inflow from additional borrowings, net of cash paid to third parties in connection with debt origination. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585 + Details
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- Definition The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585 + Details
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