Note 4 - Inventory (Tables)
12 Months Ended
Dec. 31, 2015
Inventory Disclosure [Abstract]  
Schedule of Inventory, Current [Table Text Block]
   

2015

   

2014

 

At average cost (approximates current cost)

               

Finished goods

  $ 35,517     $ 25,369  

Work in process

    1,695       2,391  

Raw materials and supplies

    31,247       25,935  
Total inventories at weighted average cost     68,459       53,695  

LIFO reserve

    (3,502

)

    (8,342

)

Total inventories

  $ 64,957     $ 45,353