v3.25.4
Retirement benefits - Narrative (Details)
$ in Millions
3 Months Ended 12 Months Ended
Sep. 30, 2026
Dec. 31, 2026
USD ($)
Dec. 31, 2025
USD ($)
plan
Jul. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
The Netherlands          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     $ 483   $ (4,753)
Percentage of defined benefit liability related to active members     17.00%   21.00%
Derecognised surplus       $ 5,521  
Minimum funding requirement       $ 750  
The Netherlands | Bottom of range | Forecast          
Disclosure of defined benefit plans [line items]          
Local funding threshold 125.00%        
UK          
Disclosure of defined benefit plans [line items]          
Percentage of defined benefit liability related to active members     13.00%   14.00%
Defined benefit plans funded by final salary pension arrangements | plan     4    
Number of defined benefit plans that cannot be netted | plan     3    
Defined benefit plans closed to new employees | plan     3    
Defined benefit plans open to new members | plan     2    
Actuarial funding valuation, frequency     3 years    
Actuarial funding valuation, funding ratio     108.00%    
UK | Funded pension plans          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     $ (2,632)   $ (2,603)
UK | Unfunded pension plans          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     (382)   (319)
USA          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     $ (440)   $ (638)
Percentage of defined benefit liability related to active members     34.00%   30.00%
USA | Unfunded pension plans          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     $ 742   $ 809
Pensions | Forecast          
Disclosure of defined benefit plans [line items]          
Estimate of contributions expected to be paid to plan for next annual reporting period   $ 1,061      
Pensions | The Netherlands | Bottom of range | Forecast          
Disclosure of defined benefit plans [line items]          
Estimate of contributions expected to be paid to plan for next annual reporting period   $ 293      
Pensions | The Netherlands | Top of range          
Disclosure of defined benefit plans [line items]          
Percentage of average local funding requirement for additional payments     105.00%    
OPEB | USA          
Disclosure of defined benefit plans [line items]          
Surplus (deficit)     $ 2,352   $ 2,337