INVENTORIES (Tables)
 3 Months Ended
Mar. 31, 2018
INVENTORIES  
Schedule of inventories
(in thousands)  

March 31,

2018

     December 31, 
2017		  
Raw materials and supplies   $ 22,922     $ 20,116  
Work in process     10,450       8,300  
Finished goods     10,668       9,590  
Total inventories   $ 44,040     $ 38,006