v3.26.1
Significant Events - Additional Information (Detail)
$ in Millions, R$ in Billions
 1 Months Ended 12 Months Ended
Sep. 30, 2025
USD ($)
Sep. 30, 2025
AUD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
USD ($)
Jun. 30, 2026
BRL (R$)
Oct. 31, 2024
Oct. 25, 2024
USD ($)
Oct. 25, 2024
BRL (R$)
Sep. 30, 2024
USD ($)
 [1]
Sep. 30, 2024
BRL (R$)
Jul. 31, 2024
Jun. 30, 2024
USD ($)
Jun. 28, 2024
Rate
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities     $ 3,063,000,000 $ 2,575,000,000                  
BRL/USD [member]                          
Disclosure of significant events [line items]                          
Closing foreign exchange rate | Rate                         5.56
Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Percentage of compensation     50.00%   50.00%                
Federal public prosecution office claim [member] | Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities             $ 31,700,000,000 [1] R$ 170          
Percentage of commitment made             100.00% 100.00%          
Federal public prosecution office claim [member] | Compension Paid [member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities                 $ 7,900,000,000 R$ 38      
Federal public prosecution office claim [member] | Obligation To Pay [member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities               R$ 100 18,000,000,000        
Federal public prosecution office claim [member] | Obligation To Perform [member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities                 $ 5,800,000,000 R$ 32      
Brazilian Social Contribution Levy [Member]                          
Disclosure of significant events [line items]                          
Percentage of interest in joint venture investment     50.00%                    
United Kingdom Group Action Complaint [Member] | Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Percentage of compensation           50.00%              
United Kingdom Group Action Complaint [Member] | Vale S.A [Member]                          
Disclosure of significant events [line items]                          
Percentage of proportion payable to claimants                     50.00%    
Indigenous Peoples And Traditional Communities [Member] | Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities             $ 1,400,000,000 [1] R$ 8          
Samarco dam failure                          
Disclosure of significant events [line items]                          
Percentage of charges recognised in Group's results     100.00%                    
Provision recognized     $ 5,197,000,000 $ 5,849,000,000               $ 6,505,000,000  
Percentage of reasonably possible increase in discount rate     0.50%                    
Increase (decrease) in provision due to reasonably possible increase in discount rate     $ 50,000,000                    
Samarco dam failure | Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Maximum funding cap     $ 1,000,000,000                    
Samarco dam failure | Federal public prosecution office claim [member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities | R$         R$ 155                
Samarco Mineracao S.A. [member]                          
Disclosure of significant events [line items]                          
Percentage of interest in joint venture investment     50.00% 50.00%                  
Samarco Mineracao S.A. [member] | Brazilian Social Contribution Levy [Member]                          
Disclosure of significant events [line items]                          
Gross provisions     $ 400,000,000 $ 400,000,000                  
Aggregate court deposit paid     200,000,000 200,000,000                  
Samarco Mineracao S.A. [member] | Brazilian Corporate Income Tax Rate [Member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities     1,100,000,000 1,000,000,000                  
Samarco Mineracao S.A. [member] | Brazilian Mining Royalties [member]                          
Disclosure of significant events [line items]                          
Estimated financial effect of contingent liabilities     400,000,000 400,000,000                  
Samarco Mineracao S.A. [member] | Samarco dam failure | Framework agreement [member]                          
Disclosure of significant events [line items]                          
Provision recognized     48,000,000 $ 87,000,000                  
BHP Brasil Ltda [member] | Australian Class Action Complaint [Member]                          
Disclosure of significant events [line items]                          
Settlememt amount (inclusive of interest and costs) $ 74,000,000 $ 110                      
Insurance proceeds     64,000,000                    
BHP Brasil Ltda [member] | United Kingdom Group Action Complaint [Member]                          
Disclosure of significant events [line items]                          
Percentage of proportion payable to claimants                     50.00%    
BHP Brasil Ltda [member] | Samarco dam failure | Maximum [Member] | Samarco Dam Failure Settlement Agreement [Member]                          
Disclosure of significant events [line items]                          
Funding commitments amount     1,300,000,000                    
BHP Brasil Ltda [member] | Samarco Mineracao S.A. [member]                          
Disclosure of significant events [line items]                          
Investment in Samarco     0                    
Dividends received     0                    
Profits available for distribution     $ 0                    
Percentage of interest in joint venture investment     50.00%                    
[1] USD amounts reflect those included in the announcement of the Settlement Agreement calculated based on actual transactional (historical) exchange rates related to funding provided to Fundação Renova for investment to date with future spend calculated using the 28 June 2024 BRL/USD exchange rate of 5.56.