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Real Estate Securities - Trading Securities by Collateral Type (Detail) - USD ($) $ in Thousands | Dec. 31, 2015 | Dec. 31, 2014
--- | --- | ---
Investment Holdings [Line Items] |  |
Trading securities | $ 404,011 | $ 111,606
Senior Securities |  |
Investment Holdings [Line Items] |  |
Trading securities | 254,351 | 101,753
Senior Securities | Prime |  |
Investment Holdings [Line Items] |  |
Trading securities | 248,570 | 93,802
Senior Securities | Non-prime |  |
Investment Holdings [Line Items] |  |
Trading securities | 5,781 | 7,951
Subordinate Securities | Prime |  |
Investment Holdings [Line Items] |  |
Trading securities | 149,660 | 9,853
Subordinate Securities | Real Estate Securities, Prime Mezzanine [Member] |  |
Investment Holdings [Line Items] |  |
Trading securities | 136,140 | 0
Subordinate Securities | Real Estate Securities, Prime Subordinate [Member] |  |
Investment Holdings [Line Items] |  |
Trading securities | $ 13,520 | $ 9,853

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- Definition Amount of investments in debt and equity securities and other forms of securities that provide ownership interests classified as trading. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26626-111562 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49167202&loc=d3e26610-111562 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 + Details
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