v3.25.2
Retirement benefits - Summary of Retirement Benefits by Financial Position (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Disclosure of net defined benefit liability (asset) [line items]      
Net defined benefit liability (asset) $ 1,602 $ 2,904  
Non-current assets 9,151 10,200  
Non-current liabilities: (7,549) (7,296)  
Pensions      
Disclosure of net defined benefit liability (asset) [line items]      
Non-current liabilities: (4,448) (4,417)  
OPEB      
Disclosure of net defined benefit liability (asset) [line items]      
Non-current liabilities: (3,101) (2,879)  
Obligations      
Disclosure of net defined benefit liability (asset) [line items]      
Net defined benefit liability (asset) (78,024) (73,481) $ (107,336)
Obligations | OPEB      
Disclosure of net defined benefit liability (asset) [line items]      
Net defined benefit liability (asset) (3,101) (2,879) (4,867)
Plan assets      
Disclosure of net defined benefit liability (asset) [line items]      
Net defined benefit liability (asset) 79,961 76,756 $ 104,495
Asset ceilings      
Disclosure of net defined benefit liability (asset) [line items]      
Net defined benefit liability (asset) $ (335) $ (371)