Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Assumptions used in Estimating Fair Value of Convertible Note Redemption Provision Derivative Liability (Detail)
 6 Months Ended
Nov. 15, 2019
$ / shares
Feb. 28, 2019
$ / shares
Jan. 30, 2019
$ / shares
Nov. 30, 2018
$ / shares
Nov. 15, 2018
Fair value of underlying stock          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, price per share $ 0.57   $ 0.49 $ 0.58  
Fair value of underlying stock | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, price per share   $ 0.50      
Fair value of underlying stock | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, price per share   $ 0.50      
Risk free rate          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input     0.0252 0.0278 0.0278
Risk free rate | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.0254      
Risk free rate | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.0252      
Expected Term (In Years)          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, expected term 1 year 7 months 10 days   2 years 1 year 7 months 10 days  
Expected Term (In Years) | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, expected term   1 year 3 months 29 days      
Expected Term (In Years) | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, expected term   1 year 11 months 1 day      
Stock price volatility          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input     0.61 0.588 0.588
Stock price volatility | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.61      
Stock price volatility | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.613      
Expected dividend yield          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, dividend yield 0.00%   0.00% 0.00%  
Expected dividend yield | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, dividend yield   0.00%      
Expected dividend yield | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded derivative liability, dividend yield   0.00%      
Discount factor          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input     0.85 0.85 0.85
Discount factor | June Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.85      
Discount factor | January Note          
Fair Value Measurement Inputs and Valuation Techniques [Line Items]          
Embedded Derivative Liability, Measurement Input   0.85