Retirement Benefits (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Components of Net Periodic Benefit Cost
Net periodic benefit cost (benefit)	$ (81)	$ (113)
Defined contribution plan, employer contributions	229	230
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	54	60
Interest cost	403	381
Expected return on plan assets	(540)	(549)
Amortization of prior service credit	0	0
Other	7	0
Net periodic benefit cost (benefit)	(76)	(108)
Defined benefit plan, contributions by Employer	18	25
OPB
Components of Net Periodic Benefit Cost
Service cost	1	1
Interest cost	16	15
Expected return on plan assets	(21)	(21)
Amortization of prior service credit	(1)	0
Other	0	0
Net periodic benefit cost (benefit)	(5)	(5)
Defined benefit plan, contributions by Employer	$ 10	$ 11