v3.25.4
EQUITY - Transactions with Non-controlling Interests (Details)
€ in Millions, R$ in Millions, $ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2025
USD ($)
Jun. 30, 2022
Mar. 30, 2022
Jun. 03, 2021
Apr. 01, 2018
USD ($)
time
Jun. 30, 2025
USD ($)
Jun. 30, 2025
EUR (€)
Jun. 29, 2025
Dec. 31, 2025
USD ($)
employer
Dec. 31, 2024
USD ($)
Jul. 31, 2025
USD ($)
Dec. 31, 2024
BRL (R$)
Dec. 31, 2023
USD ($)
Jan. 31, 2023
USD ($)
Dec. 31, 2022
USD ($)
Sep. 30, 2022
BRL (R$)
Apr. 01, 2018
BRL (R$)
Disclosure of subsidiaries [line items]                                  
Equity                 $ 56,536 $ 51,286     $ 56,068   $ 55,590    
Areco                                  
Disclosure of subsidiaries [line items]                                  
Proportion of ownership interests held by non-controlling interests (in percent) 38.11%             62.86%                  
Sonasid                                  
Disclosure of subsidiaries [line items]                                  
Proportion of ownership interests held by non-controlling interests (in percent)                 67.57% 67.57%              
Proportion of ownership interest in subsidiary (in percent)                 32.43%                
Finocas                                  
Disclosure of subsidiaries [line items]                                  
Number of capital increases | employer                 2                
Increase (decrease) through changes in ownership interests in subsidiaries that do not result in loss of control, equity                 $ (172) $ (172)              
Proportion of ownership interests held by non-controlling interests (in percent)                 50.00% 50.00%              
Proportion of ownership interest in subsidiary (in percent)                 50.00%                
Areco                                  
Disclosure of subsidiaries [line items]                                  
Increase (decrease) through changes in ownership interests in subsidiaries that do not result in loss of control, equity           $ 88 € 75                    
Nouvelles Sidérurgies Industrielles | Sonasid                                  
Disclosure of subsidiaries [line items]                                  
Proportion of ownership interest in subsidiary (in percent)       64.86%         64.86%                
ArcelorMittal Brasil S.A. | Other legal claims                                  
Disclosure of subsidiaries [line items]                                  
Exercise price, put option                           $ 179   R$ 5,825  
Settlement amount                     $ 546            
Tax settlement payment period                     3 years            
ArcelorMittal Brasil S.A. | Forecast | Other legal claims                                  
Disclosure of subsidiaries [line items]                                  
Settlement amount $ 546         $ 546                      
Tax settlement payment period 3 years         3 years                      
Put option with ISP                                  
Disclosure of subsidiaries [line items]                                  
Equity                 $ 153 $ 114              
Non-controlling interests                                  
Disclosure of subsidiaries [line items]                                  
Equity                 2,070 2,063     $ 2,107   2,438    
Non-controlling interests | Finocas                                  
Disclosure of subsidiaries [line items]                                  
Increase (decrease) through changes in ownership interests in subsidiaries that do not result in loss of control, equity                   (172)              
Non-controlling interests | Areco                                  
Disclosure of subsidiaries [line items]                                  
Increase (decrease) through changes in ownership interests in subsidiaries that do not result in loss of control, equity           $ 97                      
AMSF                                  
Disclosure of subsidiaries [line items]                                  
Proportion of ownership interests held by non-controlling interests (in percent)     2.90%                            
Multiple applied to ArcelorMittal Brazil Longs Business EBITDA in share price calculation | time         6                        
Identifiable liabilities assumed | R$                                 R$ 6,200
Percentage applied to net debt in share price calculation         15.00%                       15.00%
Consideration payable, acquisition-date fair value         $ 328                        
Exercise price, put option                       R$ 1,000   $ 179 $ 179    
ArcelorMittal Texas HBI LLC                                  
Disclosure of subsidiaries [line items]                                  
Proportion of ownership interest in subsidiary (in percent)   80.00%                              
Contingent liabilities recognised in business combination                 $ 175 $ 176              
ArcelorMittal Texas HBI LLC | First opportunity                                  
Disclosure of subsidiaries [line items]                                  
Exercise term, put option   20.00%                              
ArcelorMittal Texas HBI LLC | Second opportunity                                  
Disclosure of subsidiaries [line items]                                  
Exercise term, put option   10.00%                              
ArcelorMittal Texas HBI LLC | Third opportunity                                  
Disclosure of subsidiaries [line items]                                  
Exercise term, put option   6.66%