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Significant Accounting Policies - Narrative (Detail)	3 Months Ended		6 Months Ended
	Jun. 30, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2019 USD ($) Segment	Jun. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Business Organization And Significant Accounting Policies [Line Items]
Number of business segment | Segment			1
Accounts receivable, related parties	$ 9,600,000		$ 9,600,000		$ 9,400,000
Client performance period			5 years
Revenue	33,545,016	$ 35,927,715	$ 66,124,389	$ 73,709,717
Advance commissions amortization period			12 months
Variable Rate Fees
Business Organization And Significant Accounting Policies [Line Items]
Revenue	$ 0	$ 0	$ 0	$ 0

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