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Significant Accounting Policies - Mutual Fund Administration Gross and Net Revenue (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenue from External Customer [Line Items]
Revenue	$ 31,175,755	$ 34,592,372	$ 91,350,429	$ 100,716,763
Administration revenue, gross
Revenue from External Customer [Line Items]
Revenue	5,571,022	5,677,414	16,144,295	16,599,581
Fund related expense
Revenue from External Customer [Line Items]
Expenses	3,766,667	3,589,273	11,028,882	10,430,419
Revenue, net of related expenses
Revenue from External Customer [Line Items]
Revenue	1,804,355	2,088,141	5,115,413	6,169,162
Broker Commission
Revenue from External Customer [Line Items]
Revenue	60,634	57,908	190,993	176,901
Expenses	51,886	51,778	175,302	150,791
Financing activity, net
Revenue from External Customer [Line Items]
Revenue	8,748	6,130	15,691	26,110
Mutual fund administration revenue, net
Revenue from External Customer [Line Items]
Revenue	$ 1,813,103	$ 2,094,271	$ 5,131,104	$ 6,195,272

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