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Significant Accounting Policies - Textual (Details) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2018 USD ($) Segment | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Jan. 01, 2019 USD ($) | Jan. 01, 2016 USD ($)
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Cumulative-effect adjustment from the adoption of ASU 2015-02 (Note 2) |  |  |  |  | $ 4,031,756
Number of business segment | Segment | 1 |  |  |  |
Allowance for doubtful accounts | $ 0 | $ 0 |  |  |
Accounts receivable, related parties | 9,400,000 | 11,600,000 |  |  |
Accumulated depreciation | $ 5,200,000 | 4,000,000 |  |  |
Client performance period | 5 years |  |  |  |
Revenue | $ 145,627,748 | 145,201,729 | $ 136,103,075 |  |
Advance commissions amortization period | 12 months |  |  |  |
Variable rate fees |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Revenue | $ 1,400,000 | 200,000 | 6,400,000 |  |
Mutual fund administration revenue, net |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Revenue | 10,309,943 | 12,513,267 | 14,457,926 |  |
Mutual fund administration revenue, net | Affiliated Entity |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Revenue from related parties | $ 10,300,000 | $ 12,500,000 | $ 11,900,000 |  |
Accounting Standards Update 2015-02 |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Cumulative-effect adjustment from the adoption of ASU 2015-02 (Note 2) |  |  |  |  | $ 4,000,000
Accounting Standards Update 2016-02 | Scenario, Forecast |  |  |  |  |
Business Organization And Significant Accounting Policies [Line Items] |  |  |  |  |
Right-of-use asset, operating leases |  |  |  | $ 3,600,000 |
Lease liability, operating leases |  |  |  | $ 3,600,000 |

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