Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 95	$ 108	$ 99
Interest cost	166	158	186
Expected return on plan assets	(346)	(339)	(334)
Amortization of:
Net actuarial loss	115	196	171
Prior service cost (credit)	(1)	0	1
Settlements	94	16	25
Net pension cost/other postretirement cost (credit)	$ 123	$ 139	$ 148