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Significant Accounting Policies - Mutual Fund Administration Gross and Net Revenue (Detail) - USD ($) | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Revenue from External Customer [Line Items] |  |
Revenue | $ 31,925,745 | $ 32,579,373
Administration revenue, gross |  |
Revenue from External Customer [Line Items] |  |
Revenue | 5,592,658 | 5,402,728
Fund related expense |  |
Revenue from External Customer [Line Items] |  |
Expenses | 3,827,249 | 3,349,541
Revenue, net of related expenses |  |
Revenue from External Customer [Line Items] |  |
Revenue | 1,765,409 | 2,053,187
Broker Commission |  |
Revenue from External Customer [Line Items] |  |
Revenue | 63,542 | 65,212
Expenses | 60,886 | 51,744
Financing activity, net |  |
Revenue from External Customer [Line Items] |  |
Revenue | 2,656 | 13,468
Mutual fund administration revenue, net |  |
Revenue from External Customer [Line Items] |  |
Revenue | $ 1,768,065 | $ 2,066,655

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