v3.26.3
Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Pension        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 1 $ 3 $ 5 $ 7
Interest cost 654 669 1,965 2,007
Expected return on plan assets (717) (769) (2,155) (2,308)
Amortization of prior service credits (16) (18) (52) (55)
Recognized net actuarial loss (gain) 155 76 465 229
Net periodic benefit cost/(income) 77 (39) 228 (120)
Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 12 13 37 38
Interest cost 30 34 90 102
Expected return on plan assets (3) (3) (9) (9)
Amortization of prior service credits (1) (1) (3) (1)
Recognized net actuarial loss (gain) (35) (35) (105) (106)
Net periodic benefit cost/(income) 3 8 10 24
Income Statement Location [Axis]: us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | Pension        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes 76 (39) 225 (120)
Income Statement Location [Axis]: us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest | Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes 3 8 10 24
Income Statement Location [Axis]: us-gaap:OperatingIncomeLoss | Pension        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes 3 2 7
Income Statement Location [Axis]: us-gaap:OperatingIncomeLoss | Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes 12 13 37 38
Income Statement Location [Axis]: us-gaap:OtherNonoperatingIncomeExpense | Pension        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes 76 (42) 223 (127)
Income Statement Location [Axis]: us-gaap:OtherNonoperatingIncomeExpense | Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Net periodic benefit cost/(income) included in earnings/(loss) from operations, other income, net and loss before income taxes $ (9) $ (5) $ (27) $ (14)