Intangible Assets, Net - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Finite Lived Intangible Assets Accumulated Amortization Addition	$ 4,164,056	$ 4,302,090	$ 12,770,578	$ 12,999,407
Exclusivity [Member]
Finite Lived Intangible Assets Accumulated Amortization Addition	$ 106,000	$ 106,000	$ 318,000	$ 318,000