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Inventories
9 Months Ended
Sep. 30, 2025
Inventory Disclosure [Abstract]  
Inventories . Inventories

We value our raw materials, work in process, and finished goods inventories using lower of cost, as determined by the average cost method, or net realizable value. Supplies and materials are valued at the first-in, first-out (FIFO) or average cost method.

The components of inventories were as follows (dollars in millions):

 

 

 

September 30,

 

 

December 31,

 

 

 

2025

 

 

2024

 

Raw materials

 

$

423.2

 

 

$

356.6

 

Work in process

 

 

19.4

 

 

 

15.5

 

Finished goods

 

 

255.3

 

 

 

234.0

 

Supplies and materials

 

 

579.2

 

 

 

518.8

 

Inventories

 

$

1,277.1

 

 

$

1,124.9