Subsequent Event - Additional Information (Detail) - At-the-Market Offering [Member] - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Subsequent Event [Line Items]
Common stock issued		6,029,465	1,707,995	6,029,465	1,707,995
Weighted average common stock price per share		$ 0.81	$ 1.50	$ 0.81	$ 1.50
Gross proceeds from issuance of common stock		$ 4,900,000	$ 2,600,000	$ 4,900,000	$ 2,600,000
Share issuance costs		$ 250,000	$ 151,000	$ 250,000	$ 151,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Common stock issued	12,093,492
Weighted average common stock price per share	$ 0.49
Gross proceeds from issuance of common stock	$ 5,900,000
Share issuance costs	$ 266,000