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Investment Portfolio - Summary of Market Value of Investments (Detail) - USD ($) | Sep. 30, 2016 | Dec. 31, 2015
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Investment Holdings [Line Items] |  |
Seed capital equity method investments | $ 27,952,788 |
Deferred compensation investments | 13,369,919 |
Total Investment portfolio | 87,047,844 | $ 52,490,820
Securities held in Consolidated Funds |  |
Investment Holdings [Line Items] |  |
Trading investments | 45,704,913 |
Securities held in Consolidated Funds | Total |  |
Investment Holdings [Line Items] |  |
Trading investments | 41,600,000 |
Securities held in Consolidated Funds | Redeemable Noncontrolling Interest |  |
Investment Holdings [Line Items] |  |
Trading investments | 4,100,000 |
Securities held in Consolidated Funds | Fair Value, Measurements, Recurring [Member] |  |
Investment Holdings [Line Items] |  |
Trading investments | 45,704,913 |
Seed capital investments |  |
Investment Holdings [Line Items] |  |
Trading investments | 20,224 |
Seed capital investments | Fair Value, Measurements, Recurring [Member] |  |
Investment Holdings [Line Items] |  |
Trading investments | $ 20,224 |

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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=66022249&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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