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Real Estate Securities - Trading Securities by Collateral Type (Details) - USD ($) $ in Thousands | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Investment Holdings [Line Items] |  |
Real estate securities | $ 144,162 | $ 860,540
Senior IO Securities |  |
Investment Holdings [Line Items] |  |
Real estate securities | 28,091 | 150,067
Subordinate Securities | Mezzanine |  |
Investment Holdings [Line Items] |  |
Real estate securities | 3,651 | 538,489
Subordinate Securities | Subordinate |  |
Investment Holdings [Line Items] |  |
Real estate securities | $ 112,420 | $ 171,984

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- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in net income (trading) and investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.4) -URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878 + Details
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