Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Non-service Cost or Income Components	$ 295	$ 184	$ 136
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	79	128	134
Interest cost	221	163	152
Expected return on plan assets(b)	(333)	(320)	(297)
Prior service credit	0	0	0
Actuarial (gain) loss	(115)	25	73
Defined Benefit Plan, Non-service Cost or Income Components	(227)	(132)	(72)
Net periodic benefit cost (income)(d)	$ (148)	(4)	62
Defined Benefit Plan, Amortization of Gain (Loss)	10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period	4 years
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 12	20	23
Interest cost	45	34	33
Expected return on plan assets(b)	(91)	(85)	(80)
Prior service credit	(4)	(4)	(4)
Actuarial (gain) loss	(45)	(19)	(6)
Defined Benefit Plan, Non-service Cost or Income Components	(95)	(74)	(57)
Net periodic benefit cost (income)(d)	$ (83)	$ (54)	$ (34)
Defined Benefit Plan, Amortization of Gain (Loss)	10 years
Defined Benefit Plan, Difference Between Actual and Expected Return (Loss) on Plan Assets Amortization Period	4 years