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

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

v2.4.0.8
Estimated Fair Value of Options and Warrants Determined Using Black-Scholes Option Valuation Model with Weighted-Average Assumptions (Detail) (USD $)
12 Months Ended
May 31, 2013
May 31, 2012
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]    
Risk free rate, minimum 0.12% 0.12%
Risk free rate, maximum 0.70% 0.87%
Dividend yield      
Volatility, minimum 87.00% 93.00%
Volatility, maximum 102.00% 102.00%
Minimum
   
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]    
Expected term, maximum 1 year 1 year
Maximum
   
Share Based Compensation Arrangements By Share Based Payment Award Options [Line Items]    
Expected term, maximum 4 years 4 years