Retirement Benefits (Changes In Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Change in fair value of plan assets
Beginning balance	$ 1,818	$ 2,012
Actual return on plan assets	329	(76)
Employer contributions	4	4
Benefits paid	(125)	(122)
Ending balance	2,026	1,818
Other Benefits [Member]
Change in fair value of plan assets
Beginning balance	336	356
Actual return on plan assets	55	(17)
Employer contributions	5	49
Benefits paid	(29)	(52)
Ending balance	$ 367	$ 336