Note 15 - Derivative Financial Instruments (Tables)
 12 Months Ended
May. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]  
Schedule of Interest Rate Derivatives [Table Text Block]
   

As of May 31

  
   

2015

    

2014

  
                 

Interest rate swaps (included in other liabilities)

   $ (686 )     (1,357 )
Derivative Instruments, Gain (Loss) [Table Text Block]
   

Year Ended May 31

  

Location of (loss) gain reclassified from AOCI into income

  

2015

    

2014

  
                 

(Losses) gains on cash flow hedges:

                

Interest expense (effective portion)

  $ (907 )     (1,001 )

Interest income (expense) (ineffective portion)

   $ (3 )     (10 )