v3.26.1
INVENTORIES - Summary of Inventories (Details) - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Class Of Inventories [Line Items]    
Raw materials $ 1,356.1 $ 1,218.0
Work in process 995.4 840.9
Spare parts 466.4 437.4
Finished goods 77.1 76.8
Held by third parties 93.2 107.7
Advances to suppliers 82.4 39.1
Inventory in transit 132.2 163.2
Consumption materials 64.3 53.0
Total 3,267.1 2,936.1
Gross book value    
Class Of Inventories [Line Items]    
Raw materials 1,443.8 1,302.6
Work in process 995.4 840.9
Spare parts 510.2 476.5
Finished goods 77.1 76.8
Held by third parties 97.2 112.2
Advances to suppliers 82.4 39.1
Inventory in transit 132.2 163.2
Consumption materials 67.5 58.4
Total 3,405.8 3,069.7
Write-down for obsolescence    
Class Of Inventories [Line Items]    
Raw materials (87.7) (84.6)
Work in process 0.0 0.0
Spare parts (43.0) (38.2)
Finished goods 0.0 0.0
Held by third parties (4.0) (4.5)
Advances to suppliers 0.0 0.0
Inventory in transit 0.0 0.0
Consumption materials (3.2) (5.4)
Total (137.9) (132.7)
Write-down for market value    
Class Of Inventories [Line Items]    
Raw materials 0.0 0.0
Work in process 0.0 0.0
Spare parts (0.8) (0.9)
Finished goods 0.0 0.0
Held by third parties 0.0 0.0
Advances to suppliers 0.0 0.0
Inventory in transit 0.0 0.0
Consumption materials 0.0 0.0
Total $ (0.8) $ (0.9)