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Investments (Tables)
9 Months Ended
Feb. 28, 2013
Investments [Abstract]  
Summary of investments

The following is a summary of investments:

 

                         
    Gross
Amortized
Costs
    Gross
Unrealized
(Losses)
Gains
    Fair
Value
 
    (Dollars in thousands)  

February 28, 2013

                       

U. S. Treasury Bills

  $ 6,000     $  —       $ 6,000  
   

 

 

   

 

 

   

 

 

 

May 31, 2012

                       

U. S. Treasury Bills

  $ 16,998     $ 5     $ 17,003