Net Loss per Share - Numerator and Denominator Used in Computing Basic and Diluted Net Loss per Share (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Numerator:
Net loss	$ (5,370,846)	$ (5,379,947)
Denominator:
Weighted-average shares outstanding-basic and diluted	28,600,679	24,704,128
Net loss per share, basic and diluted	$ (0.19)	$ (0.22)