v3.25.4
Employee Benefits - Fair Values For Other Postretirement Benefit Plans By Asset Category (Detail) - Health Care and Life - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount $ 498 $ 466 $ 466
Fair Value, Inputs, Level 1, 2 and 3      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 498 463  
Fair Value, Inputs, Level 1, 2 and 3 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 32 21  
Fair Value, Inputs, Level 1, 2 and 3 | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 237 223  
Fair Value, Inputs, Level 1, 2 and 3 | U.S. Treasuries and agencies      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 165 149  
Fair Value, Inputs, Level 1, 2 and 3 | Corporate bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 39 45  
Fair Value, Inputs, Level 1, 2 and 3 | International bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 13 15  
Fair Value, Inputs, Level 1, 2 and 3 | Other      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 12 10  
Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 418 401  
Level 1 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 1 | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 237 223  
Level 1 | U.S. Treasuries and agencies      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 150 135  
Level 1 | Corporate bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 22 32  
Level 1 | International bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 9 11  
Level 1 | Other      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 80 62  
Level 2 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 32 21  
Level 2 | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 2 | U.S. Treasuries and agencies      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 15 14  
Level 2 | Corporate bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 17 13  
Level 2 | International bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 4 4  
Level 2 | Other      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 12 10  
Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | Equity securities      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | U.S. Treasuries and agencies      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | Corporate bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | International bonds      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Level 3 | Other      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount 0 0  
Investments measured at NAV      
Defined Benefit Plan Disclosure [Line Items]      
Defined benefit plan, plan assets amount $ 0 $ 3