Retirement Benefits (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Components of Net Periodic Benefit Cost
Net periodic benefit cost (benefit)	$ (113)	$ (76)
Defined contribution plan, employer contributions	230	215
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	60	59
Interest cost	381	392
Expected return on plan assets	(549)	(524)
Net periodic benefit cost (benefit)	(108)	(73)
Defined benefit plan, contributions by Employer	25	29
OPB
Components of Net Periodic Benefit Cost
Service cost	1	1
Interest cost	15	17
Expected return on plan assets	(21)	(21)
Net periodic benefit cost (benefit)	(5)	(3)
Defined benefit plan, contributions by Employer	$ 11	$ 11