Annual report pursuant to section 13 and 15(d)

Common Stock and Common Stock Payable Issued for Services - Additional Information (Detail)

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Common Stock and Common Stock Payable Issued for Services - Additional Information (Detail) (USD $)
 1 Months Ended 12 Months Ended
Dec. 28, 2012
May 31, 2013
May 31, 2012
May 31, 2011
May 31, 2010
May 31, 2009
May 31, 2008
May 31, 2007
Common Stock Issued For Services [Line Items]                
Common stock issued 66,116              
Stock-based compensation recognized   $ 3,261,951 $ 1,692,290 $ 952,316 $ 1,671,118 $ 371,996 $ 461,602 $ 535,984
Settlement of trade payable 447,000              
Cash payment for service from previous principal law firm 45,000              
Common stock issued for service from previous principal law firm, value 80,000     184,500   6,468    
Gain on satisfaction of trade payables   322,000            
Transaction 02
                
Common Stock Issued For Services [Line Items]                
Common stock issued   108,000 400,000          
Stock-based compensation recognized     388,000          
Director | Transaction 01
                
Common Stock Issued For Services [Line Items]                
Common stock issued   51,520            
Stock-based compensation recognized   49,000 35,000          
Director | Transaction 01 | Minimum
                
Common Stock Issued For Services [Line Items]                
Issue price per share   $ 0.80            
Director | Transaction 01 | Maximum
                
Common Stock Issued For Services [Line Items]                
Issue price per share   $ 1.60            
Director | Transaction 02
                
Common Stock Issued For Services [Line Items]                
Common stock issued   10,000            
Consultant
                
Common Stock Issued For Services [Line Items]                
Common stock issued   60,000            
Issue price per share   $ 2.68            
Stock-based compensation recognized   $ 161,000 $ 203,000