v3.26.1
Post employment benefits - Plan assets and liabilities by type of post employment benefit and country (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2024
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country $ 627 $ 757 $ 721
Plan assets      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 8,057 8,533 8,417
Plan liabilities      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (7,430) (7,776) $ (7,696)
Pensions | Plan assets | United Kingdom      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 5,271 5,640  
Pensions | Plan assets | Ireland      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 1,938 2,057  
Pensions | Plan assets | United States      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 623 595  
Pensions | Plan assets | Other      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 203 215  
Pensions | Plan liabilities | United Kingdom      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (4,800) (5,083)  
Pensions | Plan liabilities | Ireland      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (1,533) (1,599)  
Pensions | Plan liabilities | United States      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (590) (562)  
Pensions | Plan liabilities | Other      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (210) (230)  
Post-employment medical | Plan assets      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 2 3  
Post-employment medical | Plan liabilities      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country (257) (266)  
Other post-employment | Plan assets      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country 20 23  
Other post-employment | Plan liabilities      
Disclosure of net defined benefit liability (asset) [line items]      
Plan asset and liabilities by type and country $ (40) $ (36)