v3.25.4
Pension plans - Projected benefit obligation, plan assets and net funded status (Detail) - Pension Plans, Defined Benefit [Member] - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Plan assets      
Balance at the beginning of the year $ 14,180 $ 13,379  
Employer contributions 108 111  
Benefits paid (1,084) (810)  
Settlements paid (115) (354)  
Actual return on plan assets 319 1,909  
Other 185 (55)  
Balance at the end of the year 13,593 14,180 $ 13,379
Benefit obligations      
Balance at the beginning of the year 11,720 12,767  
Service cost 95 107 111
Interest cost $ 627 $ 617 640
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Interest Cost, Statement of Income or Comprehensive Income [Extensible Enumeration] Interest Expense, Operating and Nonoperating Interest Expense, Operating and Nonoperating  
Benefits paid $ (1,084) $ (810)  
Settlements paid (115) (354)  
Actuarial (gains) losses and other 296 (607)  
Balance at the end of the year 11,539 11,720 $ 12,767
Net funded status - asset (liability) 2,054 2,460  
Balances included in other assets 3,100 3,490  
Balances included in accounts payable and other liabilities $ 1,046 $ 1,030