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Investment Portfolio - Summary of Market Value of Investments (Detail) - USD ($)	Jun. 30, 2018	Dec. 31, 2017
Investment Holdings [Line Items]
Company sponsored equity method investments	$ 19,475,312	$ 36,043,704
Total Investment portfolio	205,200,638	138,476,022
Securities held in Consolidated Funds
Investment Holdings [Line Items]
Fair value investments	148,949,537	65,890,500
Securities held in Consolidated Funds | Parent
Investment Holdings [Line Items]
Fair value investments	86,300,000	42,600,000
Securities held in Consolidated Funds | Redeemable Noncontrolling Interest
Investment Holdings [Line Items]
Fair value investments	62,700,000	23,300,000
Company sponsored investments
Investment Holdings [Line Items]
Fair value investments	$ 36,775,789	$ 36,541,818

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