Warrants - (Detail) - USD ($)	1 Months Ended	9 Months Ended
	Oct. 31, 2019	Sep. 30, 2019	Sep. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Aug. 31, 2018	Aug. 13, 2018
Class of Warrant or Right [Line Items]
Warrants, Exercise price		$ 0.51			$ 0.51
Warrant derivative liability		$ 8,165,955			$ 6,933,031
Proceeds from warrant exercises		$ 350,000	$ 2,969,119
Investor Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants, Exercise price		$ 0.40
Issuance of common stock (Shares)		875,000
Proceeds from warrant exercises		$ 350,000
Placement Agent Warrants [Member]
Class of Warrant or Right [Line Items]
Warrants to purchase common stock, shares				2,100,000
Warrants, Exercise price				$ 0.50
Warrant, Term				5 years
Confidentially Marketed Public Offering | 2018 public offerings
Class of Warrant or Right [Line Items]
Warrants to purchase common stock, shares						20,000,000
Warrants, Exercise price						$ 0.40
Warrant, Term		3 years 10 months 13 days			4 years 7 months 13 days	5 years	5 years
Warrants outstanding, Fair value		$ 6,100,000
Warrant Exercise Agreement
Class of Warrant or Right [Line Items]
Warrants, Exercise price	$ 0.215
Proceeds from warrant exercises	$ 3,200,000
Warrant Exercise Agreement | 2018 public offerings
Class of Warrant or Right [Line Items]
Warrants, Exercise price	$ 0.40
Warrant Exercise Agreement | 2017 public offering
Class of Warrant or Right [Line Items]
Warrants, Exercise price	$ 0.76