v3.26.1
Retirement Benefits - Calculation 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
Amortization of:        
Non-service net periodic benefit cost $ (11) $ (13) $ (21) $ (26)
Pension Plan, Defined Benefit [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 40 39 80 77
Interest cost 142 147 285 293
Expected return on assets (176) (178) (352) (356)
Amortization of:        
Prior service credit 0 0 1 1
Actuarial loss (gain) 50 53 100 106
Non-service net periodic benefit cost 56 61 114 121
Other Postretirement Benefit Plan, Defined Benefit [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 7 6 14 12
Interest cost 25 25 50 50
Expected return on assets (21) (21) (43) (42)
Amortization of:        
Prior service credit (2) (2) (4) (4)
Actuarial loss (gain) (1) (1) (1) (1)
Non-service net periodic benefit cost $ 8 $ 7 $ 16 $ 15