Annual report pursuant to Section 13 and 15(d)

Weighted Average Assumptions to Value Investor Warrants (Detail)

v3.5.0.2
Weighted Average Assumptions to Value Investor Warrants (Detail) - $ / shares
12 Months Ended
May 31, 2016
May 31, 2015
Detachable Common Stock Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Expected dividend yield 0.00% 0.00%
Stock price volatility   80.68%
Expected term 1 year 50 years
Risk-free interest rate 0.33% 0.12%
Grant-date fair value   $ 0.15
Investor Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Expected dividend yield   0.00%
Stock price volatility   88.79%
Expected term   5 years
Minimum | Detachable Common Stock Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Stock price volatility 64.56%  
Grant-date fair value $ 0.15  
Minimum | Investor Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Risk-free interest rate   1.46%
Grant-date fair value   $ 0.52
Maximum | Detachable Common Stock Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Stock price volatility 69.30%  
Grant-date fair value $ 0.18  
Maximum | Investor Warrants    
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]    
Risk-free interest rate   1.58%
Grant-date fair value   $ 0.76