Annual report pursuant to Section 13 and 15(d)

Financial Instruments - Summary of Quantitative Information with Respect to Significant Unobservable Inputs (Detail)

v3.19.1
Financial Instruments - Summary of Quantitative Information with Respect to Significant Unobservable Inputs (Detail)
Dec. 31, 2018
Apr. 06, 2018
May 17, 2017
Volatility [Member] | April 2018 Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input 70 70  
Volatility [Member] | Bridge Loan [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input 70    
Volatility [Member] | 10% Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input     70
Risk-free Rate [Member] | April 2018 Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input 2.51 2.58  
Risk-free Rate [Member] | Bridge Loan [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input 2.40    
Risk-free Rate [Member] | 10% Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input     1.44
Discount for Lack of Marketability [Member] | Bridge Loan [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input 10    
Discount for Lack of Marketability [Member] | 10% Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants, measurement input     0
Term [Member] | April 2018 Warrant [Member]      
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]      
Warrants term 4 years 3 months 5 years