Registered Offering and Warrants - Schedule of Pre-funded Warrants and Warrants Outstanding (Detail)	9 Months Ended
	Sep. 30, 2020 $ / shares shares
Class Of Warrant Or Right [Line Items]
Warrant exercise price | $ / shares	$ 5.95
Warrant issued	30,750,000
Warrant exercised	(11,750,000)
Ending Balance	19,000,000
Pre funded Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrant description	Pre-Funded Warrants
Warrant classification	Liability
Warrant exercise price | $ / shares	$ 0.0001
Warrant expiration date	Mar. 17, 2025
Warrant issued	11,750,000
Warrant exercised	(11,750,000)
Warrants [Member]
Class Of Warrant Or Right [Line Items]
Warrant description	Warrants
Warrant classification	Liability
Warrant exercise price | $ / shares	$ 5.95
Warrant expiration date	Mar. 17, 2025
Warrant issued	19,000,000
Ending Balance	19,000,000