Warrants - Summary of Assumptions Used to Estimate Fair Value of Warrants (Detail) - Common Stock Warrants [Member]	Dec. 31, 2019	Dec. 31, 2018
Expected Volatility [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of warrants, measurement input	89.87	93.90
Expected Term (Years) [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of warrants, measurement input, expected term (years)	2 years 7 months 17 days	3 years 7 months 6 days
Risk-free Interest Rate [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of warrants, measurement input	1.61	2.48
Expected Dividend Yield [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair value of warrants, measurement input	0.00	0.00