Warrants - Schedule of Assumptions Utilized in the Valuation of Warrant (Detail)	Sep. 30, 2020 yr
Risk-free Interest Rate [Member] | February 2019 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.0156
Risk-free Interest Rate [Member] | February 2020 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.0139
Risk-free Interest Rate [Member] | February 2019 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.0243
Expected Life [Member] | February 2019 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	3.36
Expected Life [Member] | February 2020 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	2.81
Expected Life [Member] | February 2019 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	3.82
Expected Volatility of Underlying Stock [Member] | February 2019 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.6401
Expected Volatility of Underlying Stock [Member] | February 2020 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.9171
Expected Volatility of Underlying Stock [Member] | February 2019 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0.8262
Expected Dividend Yield [Member] | February 2019 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0
Expected Dividend Yield [Member] | February 2020 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0
Expected Dividend Yield [Member] | February 2019 Offering [Member] | Roth 2017 Warrants [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value assumptions	0