Quarterly report pursuant to Section 13 or 15(d)

Stock Options and Warrants - Additional Information (Detail)

v3.19.3
Stock Options and Warrants - Additional Information (Detail) - USD ($)
3 Months Ended
Aug. 31, 2019
Aug. 31, 2018
Aug. 29, 2019
May 22, 2019
Aug. 24, 2017
Mar. 31, 2016
Feb. 28, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Compensation expense $ 580,727 $ 283,346          
Placement Agent              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants to purchase common shares, shares     498,105        
Term of warrants     5 years        
Exercise price of warrants, per share     $ 0.40        
Investor | Series C Convertible Preferred Stock [Member]              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants to purchase common shares, shares 2,631,000            
Term of warrants 5 years            
Exercise price of warrants, per share $ 0.50            
Subscription Agreements              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants to purchase common shares, shares     2,819,750        
Term of warrants     5 years        
Exercise price of warrants, per share     $ 0.45        
2012 Equity Incentive Plan              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Compensation expense $ 581,000 283,000          
Grant date fair value of options and warrants 542,000 $ 692,000          
Unrecognized compensation expense $ 1,000,000            
Weighted average period over which unrecognized compensation expense is expected to be recognized 10 months 2 days            
2012 Equity Incentive Plan | Employee Stock Option One | Range Two              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock option granted, exerices price $ 0.90            
2012 Equity Incentive Plan | Employee Stock Option One | Director | Range One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock option granted, Shares 600,000            
Stock option granted, exerices price $ 0.52            
Vesting period 1 year            
Stock options, term 10 years            
2012 Equity Incentive Plan | Employee Stock Option One | Executive Management and Employees | Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options grant date fair value $ 0.23            
2012 Equity Incentive Plan | Employee Stock Option One | Executive Management and Employees | Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options grant date fair value 0.30            
2012 Equity Incentive Plan | Employee Stock Option One | Managing Director | Range One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options grant date fair value $ 0.26            
2012 Equity Incentive Plan | Stock Options              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for future stock-based grants 9,949,144            
2012 Equity Incentive Plan | Stock Options | Before Amendment              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for future issuance       15,000,000 7,000,000 5,000,000 3,000,000
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 15,000,000 7,000,000 5,000,000
2012 Equity Incentive Plan | Stock Options | Executive Management and Employees              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock option granted, Shares 275,000            
Vesting period 3 years            
Stock options, term 10 years            
Warrants to purchase common shares, shares 50,000            
2012 Equity Incentive Plan | Stock Options | Executive Management and Employees | Range One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock option granted, exerices price $ 0.43            
2012 Equity Incentive Plan | Stock Options | Executive Management and Employees | Range Two              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock option granted, exerices price $ 0.52