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Significant Accounting Policies - Mutual Fund Administration Gross and Net Revenue (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenue from External Customer [Line Items]
Revenue	$ 34,592,372	$ 37,471,647	$ 100,716,763	$ 111,181,363
Administration revenue, gross
Revenue from External Customer [Line Items]
Revenue	5,677,414	6,169,984	16,599,581	18,771,040
Fund related expense
Revenue from External Customer [Line Items]
Expenses	3,589,273	3,638,618	10,430,419	10,702,498
Revenue, net of related expenses
Revenue from External Customer [Line Items]
Revenue	2,088,141	2,531,366	6,169,162	8,068,542
Broker Commission
Revenue from External Customer [Line Items]
Revenue	57,908	84,248	176,901	264,107
Expenses	51,778	72,172	150,791	237,053
Financing activity, net
Revenue from External Customer [Line Items]
Revenue	6,130	12,076	26,110	27,054
Mutual fund administration revenue, net
Revenue from External Customer [Line Items]
Revenue	$ 2,094,271	$ 2,543,442	$ 6,195,272	$ 8,095,596

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section 50
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