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Investments - Textual (Details) - Securities held in Consolidated Funds - USD ($) | Dec. 31, 2018 | Dec. 31, 2017
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Debt and Equity Securities, FV-NI [Line Items] |  |
Trading Investments | $ 153,730,480 | $ 65,890,500
Parent |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Trading Investments | 84,700,000 | 42,600,000
Redeemable Noncontrolling Interest |  |
Debt and Equity Securities, FV-NI [Line Items] |  |
Trading Investments | $ 69,000,000 | $ 23,300,000

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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=6876686&loc=d3e534808-122878 + Details
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