Quarterly report pursuant to sections 13 or 15(d)

Rescission Liabilities - Additional Information (Detail)

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Rescission Liabilities - Additional Information (Detail) (USD $)
 9 Months Ended
Feb. 28, 2013
Claim
May 31, 2012
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]    
Possible claims by investors $ 6,400,000  
Possible claims by potential state or foreign jurisdiction 2,300,000  
Affirmative defenses 0  
Number of unbarred claims in state 17  
Number of unbarred claims in foreign 5  
Rescission liability 2,344,000 3,749,000
Director
    
Deferred Compensation Arrangement with Individual, Excluding Share-based Payments and Postretirement Benefits [Line Items]    
Personal Services Agreement 7  
Compensation 200,000  
Incentive compensation 50,000  
Capital received $ 500,000