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Inventories
 3 Months Ended
Mar. 31, 2018
Inventories  
Inventories

Note 4.  Inventories



Inventories are stated at lower of cost or net realizable value. Cost is determined using a weighted average cost method for raw materials and supplies, and on a first-in, first-out basis for other inventory. Inventory consisted of the following (in thousands):









 

 

 

 

 

 

 

 

 



 

 

 

 

 

 

 

 

 



 

 

March 31,

 

December 31,

 

 



 

 

2018

 

2017

 

 



 

Raw materials

$

 725,748 

 

$

 675,715 

 

 



 

Supplies

 

 386,123 

 

 

 374,515 

 

 



 

Work in progress

 

 169,441 

 

 

 128,565 

 

 



 

Finished goods

 

 318,746 

 

 

 340,552 

 

 



 

Total inventories

$

 1,600,058 

 

$

 1,519,347