Annual report pursuant to Section 13 and 15(d)

Private Securities Offerings - Additional Information (Detail)

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Private Securities Offerings - Additional Information (Detail) - USD ($)
 12 Months Ended
May 31, 2016
May 31, 2015
Sep. 21, 2015
Equity and Equity Units Offering Disclosure [Line Items]      
Convertible notes   $ 4,862,257  
Common stock, par value $ 0.001 $ 0.001  
Warrants to purchase common shares, shares 795,593    
Private Equity Offering      
Equity and Equity Units Offering Disclosure [Line Items]      
Exercise price of warrants, per share $ 0.675    
Term of warrants 5 years    
Common stock sold at private equity offering 48,659,338    
Common stock, par value $ 0.001    
Proceeds from private equity offering $ 37,600,000    
Private Equity Offering | Minimum      
Equity and Equity Units Offering Disclosure [Line Items]      
Warrant covering common stock shares purchased, percentage 50.00%    
Exercise price of warrants, per share $ 0.75    
Private Equity Offering | Maximum      
Equity and Equity Units Offering Disclosure [Line Items]      
Warrant covering common stock shares purchased, percentage 25.00%    
Exercise price of warrants, per share $ 1.00    
Private Equity Offering | Placement Agent      
Equity and Equity Units Offering Disclosure [Line Items]      
Warrants to purchase common shares, shares 4,960,314    
Aggregate cash fee $ 3,900,000    
Vested restricted stock awards 2,700,000    
Private Equity Offering | Warrants      
Equity and Equity Units Offering Disclosure [Line Items]      
Warrants to purchase common shares, shares 23,254,230    
Short-Term Convertible Notes | 6-Month Unsecured Convertible Promissory Notes      
Equity and Equity Units Offering Disclosure [Line Items]      
Convertible notes   $ 3,981,050  
Convertible note conversion price per share   $ 0.75 $ 0.675
Convertible notes term   6 months  
Convertible notes, interest rate   7.00%  
Short-Term Convertible Notes | 6-Month Unsecured Convertible Promissory Notes | Investor Warrants      
Equity and Equity Units Offering Disclosure [Line Items]      
Warrant covering common stock shares purchased, percentage   20.00%  
Exercise price of warrants, per share   $ 0.75  
Term of warrants   5 years  
Warrants to purchase common shares, shares   1,061,586