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Fair Value of Financial Instruments (Level 3 Assets) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2019 | Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Excluded amount, unsettled purchases, residential whole loans, at fair value |  | $ 194,700
Residential whole loans held at fair value for which the closing price of the purchase transaction had not occurred | $ 70,600 |
Recurring basis | Level 3 | Residential whole loans, at fair value |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance at beginning of period | 1,471,263 | 1,325,115
Purchases | 234,979 | 500,004
Changes in unrealized gain/(losses) | 47,848 | 36,725
Collection of principal | (152,011) | (199,203)
Repurchases | (1,337) | (1,807)
Transfer to REO | (219,159) | (189,571)
Balance at end of period | 1,381,583 | 1,471,263
Recurring basis | Level 3 | Term Notes Backed by MSR-Related Collateral |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Balance at beginning of period | 538,499 | 381,804
Purchases | 573,137 | 548,404
Collection of principal | (12,897) | (390,898)
Changes in unrealized gain/(losses) | 5,391 | (811)
Transfer to Level 2 | (1,104,130) | 0
Balance at end of period | $ 0 | 538,499
Residential whole loans |  |
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] |  |
Excluded amount, unsettled purchases, residential whole loans, at fair value |  | $ 194,700

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- Definition Residential Whole Loans Held at Fair Value, Purchase Transaction Committed in Previous Period, Closed in Subsequent Period + References No definition available. + Details
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- Definition Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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