v3.26.1
Postretirement Plans - Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pension        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 2 $ 3 $ 4 $ 4
Interest cost 653 669 1,311 1,338
Expected return on plan assets (717) (770) (1,438) (1,539)
Amortization of prior service credits (18) (18) (36) (37)
Recognized net actuarial loss (gain) 155 77 310 153
Net periodic benefit cost/(income) 75 (39) 151 (81)
Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 13 12 25 25
Interest cost 30 34 60 68
Expected return on plan assets (3) (3) (6) (6)
Amortization of prior service credits (1) (2)
Recognized net actuarial loss (gain) (35) (35) (70) (71)
Net periodic benefit cost/(income) 4 8 7 16
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 74 (39) 149 (81)
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 4 8 7 16
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 1 3 2 4
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 13 12 25 25
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 73 (42) 147 (85)
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) $ (4) $ (18) $ (9)