Preferred Stock - Allocation of Net Proceeds Received from Redeemable Preferred Stock Financing (Detail) - USD ($)		12 Months Ended
	Aug. 16, 2017	Dec. 31, 2018	Dec. 31, 2017
Allocation Of Net Proceeds From Redeemable Convertible Preferred Stock Financing [Line Items]
Common stock warrant liability (see Note 12)	$ 3,498,632
Embedded derivative	19,857		$ 19,857
Initial carrying value of redeemable preferred stock	7,993,885
Series B Redeemable Convertible Preferred Stock [Member]
Allocation Of Net Proceeds From Redeemable Convertible Preferred Stock Financing [Line Items]
Net proceeds from redeemable preferred stock issuance	13,018,570		13,018,570
Series B Redeemable Convertible Preferred Stock [Member] | Level 3 [Member]
Allocation Of Net Proceeds From Redeemable Convertible Preferred Stock Financing [Line Items]
Beneficial conversion feature	$ 1,506,196	$ 1,338,840	$ 167,356