Summary of Significant Accounting Policies - Summary of Calculation of Basic and Diluted Net Loss Per Share (Detail) - USD ($)	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net loss attributable to common shareholders for basic net loss per share	$ (1,760,633)	$ (1,519,468)	$ (2,303,193)	$ (1,982,786)	$ (308,443)	$ (5,243,061)	$ (1,625,969)	$ (5,052,039)	$ (7,566,080)	$ (12,229,512)
Adjustment for gain from change in fair value of dilutive warrants										(1,235,394)
Net loss used for diluted net loss per share									$ (7,566,080)	$ (13,464,906)
Weighted-average shares used to compute basic net loss per share					15,368,610	15,351,295	15,343,325	13,528,311	16,602,422	14,897,885
Adjustment to reflect assumed exercise of warrants										53,151
Weighted-average shares used to compute diluted net loss per share					15,503,583	15,351,295	15,420,954	13,528,311	16,602,422	14,951,036
Basic					$ (0.02)	$ (0.34)	$ (0.11)	$ (0.37)	$ (0.46)	$ (0.82)
Diluted					$ (0.07)	$ (0.34)	$ (0.13)	$ (0.37)	$ (0.46)	$ (0.90)