Retirement Benefits (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Components of Net Periodic Benefit Cost
Net periodic benefit cost (benefit)	$ (120)	$ (81)
Defined contribution plan, employer contributions	229	229
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	53	54
Interest cost	399	403
Expected return on plan assets	(565)	(540)
Amortization of prior service credit	0	0
Other	0	7
Net periodic benefit cost (benefit)	(113)	(76)
Defined benefit plan, contributions by Employer	22	18
OPB
Components of Net Periodic Benefit Cost
Service cost	1	1
Interest cost	15	16
Expected return on plan assets	(22)	(21)
Amortization of prior service credit	(1)	(1)
Other	0	0
Net periodic benefit cost (benefit)	(7)	(5)
Defined benefit plan, contributions by Employer	$ 11	$ 10