Quarterly report pursuant to Section 13 or 15(d)

Weighted Average Assumptions to Value Investor Warrants (Detail)

v3.6.0.2
Weighted Average Assumptions to Value Investor Warrants (Detail) - $ / shares
6 Months Ended 12 Months Ended
Sep. 15, 2016
Nov. 30, 2016
May 31, 2016
May 31, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield 0.00% 0.00%    
Stock price volatility 106.00% 103.00%    
Contractual term to maturity (years) 5 years 4 years 9 months 15 days    
Grant-date fair value $ 0.78 $ 0.67    
Risk-free interest rate 1.20% 1.81%    
Investor Warrants        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield       0.00%
Stock price volatility       88.79%
Contractual term to maturity (years)       5 years
Investor Warrants | Minimum        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Grant-date fair value       $ 0.52
Risk-free interest rate       1.46%
Investor Warrants | Maximum        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Grant-date fair value       $ 0.76
Risk-free interest rate       1.58%
Detachable Common Stock Warrants        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Expected dividend yield     0.00%  
Contractual term to maturity (years)     1 year  
Risk-free interest rate     0.33%  
Detachable Common Stock Warrants | Minimum        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Stock price volatility     64.56%  
Grant-date fair value     $ 0.15  
Detachable Common Stock Warrants | Maximum        
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]        
Stock price volatility     69.30%  
Grant-date fair value     $ 0.18