v3.26.3
Employee Benefits - Costs by Plans (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Mar. 31, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Defined Benefit Plan Disclosure [Line Items]          
Remeasurement loss (gain), net   $ (237)      
Pension          
Defined Benefit Plan Disclosure [Line Items]          
Service cost $ 56   $ 40 $ 157 $ 120
Amortization of prior service cost (credit) 49   28 131 84
Expected return on plan assets (184)   (133) (545) (401)
Interest cost 129   102 377 306
Remeasurement loss (gain), net 0   (31) (18) 14
Other components (6)   (34) (55) 3
Total 50   6 102 123
Pension | Income Statement Location [Axis]: us-gaap:CostOfGoodsAndServicesSold          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 56   34 157 103
Pension | Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 0   6 0 17
Health Care and Life          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 5   8 16 25
Amortization of prior service cost (credit) (31)   (33) (93) (97)
Expected return on plan assets (8)   (7) (22) (21)
Interest cost 135   137 399 410
Remeasurement loss (gain), net 0   0 (219) 0
Other components 96   97 65 292
Total 101   105 81 317
Health Care and Life | Income Statement Location [Axis]: us-gaap:CostOfGoodsAndServicesSold          
Defined Benefit Plan Disclosure [Line Items]          
Service cost 5   7 16 21
Health Care and Life | Income Statement Location [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense          
Defined Benefit Plan Disclosure [Line Items]          
Service cost $ 0   $ 1 $ 0 $ 4