Note 5 - Inventories, Net (Details) - Inventory - USD ($)
$ in Thousands
May. 31, 2015
May. 31, 2014
Inventory [Abstract]    
Raw materials and supplies $ 10,816 $ 12,110
Work in process 9,197 9,146
Finished goods 21,834 27,895
$ 41,847 $ 49,151