General form of registration statement for all companies including face-amount certificate companies

Stock Options and Warrants - Estimated Fair Value of Options and Warrants Determined Using Black-Scholes Option Valuation Model with Weighted-Average Assumptions (Detail)

v3.3.1.900
Stock Options and Warrants - Estimated Fair Value of Options and Warrants Determined Using Black-Scholes Option Valuation Model with Weighted-Average Assumptions (Detail) - USD ($)
12 Months Ended
Feb. 06, 2015
Sep. 26, 2014
May. 31, 2015
May. 31, 2014
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]        
Risk free rate, minimum     0.73% 0.52%
Risk free rate, maximum     1.10% 1.85%
Dividend yield     $ 0 $ 0
Volatility, minimum     74.36% 78.73%
Volatility, maximum     81.16% 92.92%
Expected term 5 years 5 years    
Minimum        
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]        
Expected term     2 years 6 months 2 years 6 months
Grant-date fair value     $ 0.33 $ 0.40
Maximum        
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]        
Expected term     3 years 6 months 3 years 6 months
Grant-date fair value     $ 0.60 $ 0.67