Quarterly report pursuant to Section 13 or 15(d)

Weighted Average Assumptions to Value Investor Warrants (Detail)

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Weighted Average Assumptions to Value Investor Warrants (Detail)
3 Months Ended
Aug. 31, 2015
$ / shares
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
Detachable Common Stock 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 | Investor Warrants  
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]  
Risk-free interest rate 1.46%
Grant-date fair value $ 0.52
Minimum | Detachable Common Stock Warrants  
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]  
Risk-free interest rate 1.46%
Grant-date fair value $ 0.52
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
Maximum | Detachable Common Stock Warrants  
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]  
Risk-free interest rate 1.58%
Grant-date fair value $ 0.76