Intangible Assets, Net - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite Lived Intangible Assets Accumulated Amortization Addition	$ 4,394,901	$ 4,374,841
Exclusivity [Member]
Finite Lived Intangible Assets Accumulated Amortization Addition	$ 106,000