Investment in Loans (Schedule of Investments in Loans) (Details) - USD ($) $ in Thousands |
Sep. 30, 2021 |
Dec. 31, 2020 |
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|---|---|---|---|---|---|---|
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Current Principal/Notional Amount | $ 1,940,279 | $ 1,417,054 | ||||
| Fair Value | [1],[2] | 1,996,529 | 1,453,480 | |||
| Residential mortgage loans | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Current Principal/Notional Amount | 1,602,548 | 1,150,303 | ||||
| Fair Value | 1,656,701 | 1,187,069 | ||||
| Commercial mortgage loans | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Current Principal/Notional Amount | 267,388 | 212,716 | ||||
| Fair Value | 267,591 | 213,031 | ||||
| Consumer loans | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Current Principal/Notional Amount | 53,515 | 48,180 | ||||
| Fair Value | 55,676 | 47,525 | ||||
| Corporate loan [Member] | ||||||
| Accounts, Notes, Loans and Financing Receivable [Line Items] | ||||||
| Current Principal/Notional Amount | 16,828 | 5,855 | ||||
| Fair Value | $ 16,561 | $ 5,855 | ||||
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