Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 108	$ 99	$ 84
Interest cost	158	186	219
Expected return on plan assets	(339)	(334)	(325)
Amortization of:
Net actuarial loss	196	171	131
Prior service cost	0	1	1
Settlements	16	25	2
Net pension cost/other postretirement cost (credit)	$ 139	$ 148	$ 112