Net Loss Per Common Share - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Earnings Per Share Basic [Line Items]
Warrants exercised	9,560,748		9,560,748
Stock issued upon exercise of stock options	$ 1,062	$ 37	$ 3,108	$ 183
Number of warrants outstanding	17,919,971		17,919,971
Warrant [Member]
Earnings Per Share Basic [Line Items]
Issuance of common stock for warrant exercises, Share	9,555,876		9,555,876
Common Stock and Pre-funded Warrants [Member]
Earnings Per Share Basic [Line Items]
Common stock called by warrants					27,480,719
Class of warrant nominal exercise price					$ 0.01
Number of warrants outstanding	17,919,971		17,919,971