v3.26.1
ACCOUNTING POLICIES (Impairment) (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Fixed assets and mining assets      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Impairment loss recognised in profit or loss, property, plant and equipment $ 18.8    
Mining assets      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Impairment loss recognised in profit or loss, property, plant and equipment $ 5.3 $ 32.4 $ 42.3
Total for all cash-generating units      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Growth rate used to extrapolate cash flow projections 2.27%    
Total for all cash-generating units | Mexico Steel GCU      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Discount rate used in current estimate of value in use 10.20%    
Total for all cash-generating units | Mexico Mining GCU      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Discount rate used in current estimate of value in use 10.60%    
Brazil | Total for all subsidiaries      
Disclosure of impairment loss and reversal of impairment loss [line items]      
Discount rate used in current estimate of value in use 10.40%