Quarterly report pursuant to Section 13 or 15(d)

Assumptions used in Estimating Fair Value of Convertible Note Redemption Provision Derivative Liability (Detail)

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Assumptions used in Estimating Fair Value of Convertible Note Redemption Provision Derivative Liability (Detail)
 1 Months Ended 6 Months Ended 12 Months Ended
Jan. 30, 2019
yr
$ / shares
Nov. 15, 2018
yr
$ / shares
Nov. 30, 2019
yr
$ / shares
May 31, 2019
yr
$ / shares
Fair value of underlying stock        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, price per share | $ / shares $ 0.49 $ 0.57    
Fair value of underlying stock | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, price per share | $ / shares     $ 0.28 $ 0.39
Fair value of underlying stock | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, price per share | $ / shares     $ 0.28 $ 0.39
Risk free rate        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input 2.52 2.78    
Risk free rate | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     1.63 2.21
Risk free rate | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     1.60 1.95
Expected Term (In Years)        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, expected term 2 years 1 year 7 months 9 days    
Expected Term (In Years) | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, expected term     6 months 25 days 1 year 25 days
Expected Term (In Years) | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, expected term     1 year 2 months 1 day 1 year 8 months 1 day
Stock price volatility        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input 61 58.8    
Stock price volatility | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     66.3 62.2
Stock price volatility | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     64.1 62.2
Expected dividend yield        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, dividend yield 0.00% 0.00%    
Expected dividend yield | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, dividend yield     0.00% 0.00%
Expected dividend yield | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded derivative liability, dividend yield     0.00% 0.00%
Discount factor        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input 85 85    
Discount factor | Note 1        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     85 85
Discount factor | Note 2        
Fair Value Measurement Inputs and Valuation Techniques [Line Items]        
Embedded Derivative Liability, Measurement Input     85 85