Preferred and Common Stock Warrants - Schedule of Outstanding Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Number of warrants
Outstanding and exercisable warrants to purchase shares preferred stock as of 12/31/2018	13,656,871	5,146,400
Conversion of warrants to purchase preferred shares to warrants for the purchase of common stock and adjusted for the Exchange Ratio and Reverse Stock Split (in shares)		(4,657,350)
Issuance of warrants for the purchase of common stock or prefunded warrants to purchase common stock		13,201,667
Exercised (in shares)		(33,846)
Outstanding and exerciseable, Number of warrants, ending balance (in shares)	13,354,403	13,656,871	5,146,400
Expired	302,468
Weighted Average Exercise Price
Outstanding and exercisable warrants to purchase preferred shares, beginning balance (in dollars per share)	$ 13.68	$ 0
Outstanding and exercisable, ending balance (in dollars per share)	$ 13.52	$ 13.68	$ 0
Weighted Average Contractual Term (Years)	3 years 8 months 12 days	4 years 7 months 6 days	4 years 2 months 12 days