Note 5 - Disclosure of Compensation Related Costs, Stock Based Payments (Tables)
 9 Months Ended
Jan. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Schedule of Share-based Compensation, Activity [Table Text Block]
   

Number of

option shares

   

Weighted

average option

exercise price

 

Outstanding at April 30, 2013

    854,809     $ 34.64  

Granted

    ---       ---  

Exercised

    (121,435 )     23.98  

Forfeited

    (2,000 )     44.39  

Outstanding at January 31, 2014

    731,374     $ 36.38  
Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

Unvested at April 30, 2013

    71,196  

Granted

    91,650  

Vested

    (14,150 )

Forfeited

    (150 )

Unvested at January 31, 2014

    148,546