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Investment Portfolio - Summary of Market Value of Investments (Detail) - USD ($) | Sep. 30, 2018 | Dec. 31, 2017
--- | --- | ---
Investment Holdings [Line Items] |  |
Company sponsored equity method investments | $ 20,132,461 | $ 36,043,704
Total Investment portfolio | 212,389,477 | 138,476,022
Securities held in Consolidated Funds |  |
Investment Holdings [Line Items] |  |
Fair value investments | 153,499,790 | 65,890,500
Securities held in Consolidated Funds | Parent |  |
Investment Holdings [Line Items] |  |
Fair value investments | 85,900,000 | 42,600,000
Securities held in Consolidated Funds | Redeemable Noncontrolling Interest |  |
Investment Holdings [Line Items] |  |
Fair value investments | 67,600,000 | 23,300,000
Company sponsored investments |  |
Investment Holdings [Line Items] |  |
Fair value investments | $ 38,757,226 | $ 36,541,818

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- Definition Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=63488139&loc=d3e12121-115841 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12.Column C.3,4) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14.Column E.2,3) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C.Column C.7) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 5 -Subparagraph (SX 210.12-13.Column C.6) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010 + Details
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