v3.26.1
OTHER LIABILITIES - NON CURRENT AND CURRENT (Narrative) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Usiminas    
Disclosure of defined benefit plans [line items]    
Post-retirement benefits guaranteed with property, plant and equipment $ 214.0  
Bottom of range    
Disclosure of defined benefit plans [line items]    
Estimate of contributions expected to be paid to plan for next five years 172.3  
Top of range    
Disclosure of defined benefit plans [line items]    
Estimate of contributions expected to be paid to plan for next five years $ 188.7  
Fair value of plan assets | Usiminas    
Disclosure of defined benefit plans [line items]    
Number of shares outstanding (shares) 34,109,762 34,109,762