Loan Agreement and Warrant to Purchase Preferred Stock - Additional Information (Detail) - USD ($)		12 Months Ended
	Jun. 23, 2017	Dec. 31, 2018	Dec. 31, 2017
Class of Warrant or Right [Line Items]
Maximum issuance of term loans	$ 10,000,000
Loan expiration date		Oct. 31, 2018
Fair value of warrants at issuance		$ 18,000
Loss related to change in fair value of warrant		$ 162,000	$ 17,000
Purchase of common stock		6,850
Issuance of common stock		$ 6,091
Prime Rate [Member]
Class of Warrant or Right [Line Items]
Floating interest rate per annum	3.00%
Series A Preferred Stock [Member]
Class of Warrant or Right [Line Items]
Warrant to purchase shares	188,702
Warrant exercise price	$ 0.7949
Warrant expiration date		Jun. 22, 2027
Shares purchase upon exercise of warrant	28,305
Additional shares purchase upon exercise of warrant	160,397
Minimum [Member]
Class of Warrant or Right [Line Items]
Floating interest rate per annum	1.00%