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Significant Accounting Policies - Mutual Fund Administration Gross and Net Revenue (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenue from External Customer [Line Items]
Revenue	$ 32,579,373	$ 37,782,002
Administrative revenue, gross
Revenue from External Customer [Line Items]
Revenue	5,402,728	6,607,337
Fund related expense
Revenue from External Customer [Line Items]
Expenses	3,349,541	3,468,325
Revenue, net of related expense
Revenue from External Customer [Line Items]
Revenue	2,053,187	3,139,012
Broker Commission
Revenue from External Customer [Line Items]
Revenue	65,212	96,478
Expenses	51,744	84,778
Financing activity, net
Revenue from External Customer [Line Items]
Revenue	13,468	11,700
Mutual fund administration, net
Revenue from External Customer [Line Items]
Revenue	$ 2,066,655	$ 3,150,712

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