Preferred and Common Stock Warrants - Additional Information (Detail) - $ / shares				9 Months Ended
	Nov. 29, 2019	Nov. 26, 2019	Apr. 16, 2019	Sep. 30, 2019	Sep. 30, 2020	Dec. 31, 2019
Class of Stock [Line Items]
Number of warrants, Issuance of warrants for the purchase of common stock (in shares)				6,035,000
Class of warrants or rights expiration period (in years)		30 days
Common stock, par value (in usd per share)					$ 0.001	$ 0.001
Class A Warrant
Class of Stock [Line Items]
Number of warrants, Issuance of warrants for the purchase of common stock (in shares)			3,900,000
Warrant exercise price (usd per share)			$ 13.20
Class B Warrants
Class of Stock [Line Items]
Number of warrants, Issuance of warrants for the purchase of common stock (in shares)	5,416,667
Warrant exercise price (usd per share)	$ 15.00
Pre Funded Warrant
Class of Stock [Line Items]
Number of warrants, Issuance of warrants for the purchase of common stock (in shares)	1,750,000		2,130,000
Warrant exercise price (usd per share)	$ 11.999		$ 10.999
Number of warrants for purchase of convertible preferred shares (in shares)			1
Common stock, par value (in usd per share)			$ 0.001