Summary of Significant Accounting Policies - Summary of Calculation of Basic and Diluted Net Loss Per Share (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Earnings Per Share [Abstract]
Net loss attributable to common shareholders for basic net loss per share	$ (1,519,468)	$ (5,243,061)	$ (5,805,448)	$ (11,921,069)
Adjustment for loss from change in fair value of warrants				(429,702)
Net loss used for diluted net loss per share	$ (1,519,468)	$ (5,243,061)	$ (5,805,448)	$ (12,350,771)
Weighted-average shares used to compute basic net loss per share	17,129,649	15,351,295	16,327,385	14,740,977
Adjustment to reflect assumed exercise of warrants				25,876
Weighted-average shares used to compute diluted net loss per share	17,129,649	15,351,295	16,327,385	14,766,853
Basic	$ (0.09)	$ (0.34)	$ (0.36)	$ (0.81)
Diluted	$ (0.09)	$ (0.34)	$ (0.36)	$ (0.84)