Retirement Benefits (Unaudited) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Components of Net Periodic Benefit Cost
Net periodic benefit cost (benefit)	$ (298)	$ (272)
Defined contribution plan, employer contributions	199	266
Pension Benefits
Components of Net Periodic Benefit Cost
Service cost	92	104
Interest cost	284	263
Expected return on plan assets	(660)	(628)
Amortization of prior service credit	0	2
Net periodic benefit cost (benefit)	(284)	(263)
Defined benefit plan, contributions by Employer	26	27
OPB
Components of Net Periodic Benefit Cost
Service cost	2	4
Interest cost	12	13
Expected return on plan assets	28	26
Amortization of prior service credit	0	0
Net periodic benefit cost (benefit)	(14)	(9)
Defined benefit plan, contributions by Employer	$ 10	$ 11