Investment in Loans Investment in Loans (Schedule of Residential Mortgage Loans: Performance) (Details) - USD ($) $ in Thousands |
Sep. 30, 2021 |
Dec. 31, 2020 |
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|---|---|---|---|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Unpaid Principal Balance | $ 1,940,279 | $ 1,417,054 | ||||
| Loans, at fair value | [1],[2] | 1,996,529 | 1,453,480 | |||
| Residential mortgage loans | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Unpaid Principal Balance | 1,602,548 | 1,150,303 | ||||
| Loans, at fair value | 1,656,701 | 1,187,069 | ||||
| Residential mortgage loans | Performing Financial Instruments [Member] | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Unpaid Principal Balance | 18,164 | 18,120 | ||||
| Loans, at fair value | 17,424 | 16,741 | ||||
| Residential mortgage loans | Non-performing | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Unpaid Principal Balance | 34,904 | 62,009 | ||||
| Loans, at fair value | $ 32,107 | $ 58,169 | ||||
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