Annual report [Section 13 and 15(d), not S-K Item 405]

ACQUISITIONS - Stelco Acquisition (Details)

v3.25.4
ACQUISITIONS - Stelco Acquisition (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Business Combination [Line Items]      
Acquisition related costs $ 1 $ 42  
Revenues 18,610 19,185 $ 21,996
Net loss attributable to acquisition $ (1,478) (760) 385
Stelco Holdings Inc      
Business Combination [Line Items]      
Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax   (629) 202
Revenues   329  
Net loss attributable to acquisition   58  
Stelco Holdings Inc | Business Combination, Pro Forma Information, Nonrecurring Adjustment, Inventory, Fair Value Adjustment      
Business Combination [Line Items]      
Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax   23 23
Stelco Holdings Inc | Business Combination, Pro Forma Information, Nonrecurring Adjustment, Acquisition-Related Cost      
Business Combination [Line Items]      
Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax   $ 63 $ 63