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Residential Whole Loans (Narrative) (Details) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2020 | Dec. 31, 2019
Receivables [Abstract] |  |
Total residential whole loans | $ 5,300,000,000 | $ 7,400,000,000
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Loss on sale of financing receivable | (800,000) |
Interest income | 0 |
Unpaid principal balance | 24,100,000 |
Non-QM Loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, sale | 1,800,000,000 |
Loss on sale of financing receivable | 273,000,000.0 |
Purchased Performing Loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, nonaccrual | 373,300,000 | $ 99,900,000
Purchased Credit Deteriorated Loans |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, nonaccrual | 151,400,000 |
Without Associated Credit Losses |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |
Financing receivable, nonaccrual | $ 130,700,000 |

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