v3.25.4
Pension and Other Postretirement Benefit Plans - Fair Values of Other Postretirement Benefit Plan Assets (Details) - Other Postretirement Benefits - USD ($)
$ in Millions
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value $ 1,107 $ 1,040 $ 1,045
Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 18 5  
Developed markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 61 49  
Emerging markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 16 24  
Real estate      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 5 3  
Developed markets      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 38 41  
Corporate obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 645 598  
Government and agency obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 261 266  
Mortgage and asset-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 63 54  
Level 1      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 55 44  
Level 1 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 14 0  
Level 1 | Developed markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 3 3  
Level 1 | Emerging markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 1 | Real estate      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 1 | Developed markets      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 38 41  
Level 1 | Corporate obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 1 | Government and agency obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 1 | Mortgage and asset-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 969 918  
Level 2 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2 | Developed markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2 | Emerging markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2 | Real estate      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2 | Developed markets      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 2 | Corporate obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 645 598  
Level 2 | Government and agency obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 261 266  
Level 2 | Mortgage and asset-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 63 54  
Level 3      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Developed markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Emerging markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Real estate      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Developed markets      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Corporate obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Government and agency obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
Level 3 | Mortgage and asset-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
NAV      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 83 78  
NAV | Cash and cash equivalents      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 4 5  
NAV | Developed markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 58 46  
NAV | Emerging markets equities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 16 24  
NAV | Real estate      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 5 3  
NAV | Developed markets      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
NAV | Corporate obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
NAV | Government and agency obligations      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value 0 0  
NAV | Mortgage and asset-backed securities      
Defined Benefit Plan Disclosure [Line Items]      
Plan assets at fair value $ 0 $ 0