Retirement Benefits (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Non-service Cost or Income Components	$ 90	$ 70	$ 44
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	88	100	93
Interest cost	187	169	179
Expected return on plan assets	(276)	(276)	(262)
Prior service credit	(1)	(1)	(1)
Actuarial (gain) loss	25	68	55
Defined Benefit Plan, Non-service Cost or Income Components	(65)	(40)	29
Net periodic benefit cost (income)	23	60	64
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	18	21	21
Interest cost	43	40	47
Expected return on plan assets	(77)	(77)	(75)
Prior service credit	(5)	(4)	(5)
Actuarial (gain) loss	(15)	(6)	(6)
Defined Benefit Plan, Non-service Cost or Income Components	(54)	(47)	(39)
Net periodic benefit cost (income)	$ (36)	$ (26)	$ (18)