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Investment Portfolio - Narrative (Detail) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Total Investments	$ 164,791,720	$ 203,488,217
Securities held in Consolidated Funds
Fair value investments	78,997,408	153,730,480
Parent | Securities held in Consolidated Funds
Fair value investments	48,800,000	84,700,000
Redeemable Noncontrolling Interest | Securities held in Consolidated Funds
Fair value investments	$ 30,200,000	$ 69,000,000

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