Quarterly report pursuant to Section 13 or 15(d)

Stock Options and Warrants - Additional Information (Detail)

v3.20.4
Stock Options and Warrants - Additional Information (Detail) - USD ($)
3 Months Ended 6 Months Ended
Sep. 30, 2020
Nov. 30, 2020
Nov. 30, 2019
Nov. 30, 2020
Nov. 30, 2019
May 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercise price of warrants, per share     $ 0.45   $ 0.45  
Common Stock issued   590,279,000   590,279,000   519,261,000
Compensation expense       $ 7,115,000 $ 1,015,000  
Common stock par or stated value per share   $ 0.001   $ 0.001   $ 0.001
Warrants            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Warrants to purchase common shares, shares   105,000   105,000    
Common Stock issued   21,600,000   21,600,000    
Proceeds from issuance of common stock       $ 15,200,000    
Stock shares issued during the period new issues shares       21,600,000    
Common stock par or stated value per share   $ 0.001   $ 0.001    
Warrants | Minimum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercise price of warrants, per share   0.30   0.30    
Warrants | Maximum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercise price of warrants, per share   $ 1.35   $ 1.35    
Compensatory Warrants [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Term of warrants   5 years   5 years    
Exercise price of warrants, per share   $ 3.07   $ 3.07    
Class of warrants or rights grant date fair value per share       $ 2.11    
Cashless Exercise Of Warrants [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock shares issued during the period new issues shares       8,900,000    
Common stock par or stated value per share   $ 0.001   $ 0.001    
Class of warrants or rights outstanding   9,600,000   9,600,000    
Cashless Exercise Of Warrants [Member] | Minimum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercise price of warrants, per share   $ 0.50   $ 0.50    
Cashless Exercise Of Warrants [Member] | Maximum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercise price of warrants, per share   $ 1.35   $ 1.35    
2012 Equity Incentive Plan            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares available for future issuance 50,000,000          
Compensation expense   $ 3,400,000 $ 1,000,000.0 $ 5,500,000 1,500,000  
Grant date fair value of options and warrants       3,000,000.0 $ 900,000  
Unrecognized compensation expense   $ 12,200,000   $ 12,200,000    
Weighted average period over which unrecognized compensation expense is expected to be recognized       1 year 2 months 1 day    
2012 Equity Incentive Plan | Employee Stock Option One            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, Shares       110,000    
Common Stock issued   110,000   110,000    
Proceeds from issuance of common stock       $ 48,300    
2012 Equity Incentive Plan | Employee Stock Option One | Minimum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, exerices price       $ 0.39    
2012 Equity Incentive Plan | Employee Stock Option One | Maximum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, exerices price       0.98    
2012 Equity Incentive Plan | Employee Stock Option One | Employees And Advisors | Minimum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock options grant date fair value       1.84    
2012 Equity Incentive Plan | Employee Stock Option One | Employees And Advisors | Maximum            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock options grant date fair value       $ 4.23    
2012 Equity Incentive Plan | Stock Options            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares available for future stock-based grants   15,700,000   15,700,000    
2012 Equity Incentive Plan | Stock Options | After Amendment            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Shares available for future issuance   25,000,000   25,000,000    
2012 Equity Incentive Plan | Stock Options | Employees And Advisors | Range One            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, exerices price       $ 2.60    
2012 Equity Incentive Plan | Stock Options | Employees And Advisors | Range Two            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, exerices price       $ 6.15    
2012 Equity Incentive Plan | Stock Options | Executive Officer [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, Shares 3,350,000          
2012 Equity Incentive Plan | Stock Options | Employees [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, Shares       1,300,000    
2012 Equity Incentive Plan | Performance Shares [Member] | Executive Officer [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Share based compensation by share based payment arrangement restricted stock shares granted during the period 4,350,000          
2012 Equity Incentive Plan | Time Based Restricted Stock Units [Member] | Executive Officer [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Share based compensation by share based payment arrangement restricted stock shares granted during the period 1,120,000          
2012 Incentive Plan Amended And Restated            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Percentage Of Increase In Shares Issued On Proportion Of Outstanding Capital Stock On Last Day Of Each Fiscal Year       1.00%    
2012 Incentive Plan Amended And Restated | Employee Stock Option One | Director            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, Shares 168,750          
2012 Incentive Plan Amended And Restated | Employee Stock Option One | Executive Officer [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock options grant date fair value $ 3.12          
2012 Incentive Plan Amended And Restated | Stock Options | Director            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, Shares 506,250          
Stock option granted, exerices price       $ 6.15    
Stock options grant date fair value       $ 4.20    
2012 Incentive Plan Amended And Restated | Stock Options | Executive Officer [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option granted, exerices price $ 3.12          
Stock options grant date fair value $ 2.12