Preferred and Common Stock Warrants - Schedule of Outstanding Warrants (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number of warrants
Outstanding and exercisable warrants to purchase preferred shares, beginning balance (in shares)	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)
Warrants issued (in shares)	13,201,667
Exercised (in shares)	(33,846)
Outstanding and exerciseable, Number of warrants, ending balance (in shares)	13,656,871	5,146,400
Weighted Average Exercise Price
Outstanding and exercisable warrants to purchase preferred shares, beginning balance (in dollars per share)	$ 0
Issuance of warrants for the purchase of common stock (in dollars per share)	13.43
Exercisable (in dollars per share)	13.20
Outstanding and exercisable, ending balance (in dollars per share)	$ 13.68	$ 0
Weighted Average Contractual Term (Years)	4 years 7 months 2 days	4 years 2 months 23 days