Retirement Benefits (Reconciliation Of The Benefit Obligation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits [Member]
Reconciliation of benefit obligation
Benefit obligation at beginning of year	$ 1,743	$ 1,872
Service cost	0	8	$ 10
Interest cost	62	55	66
Actuarial loss (gain)	200	(70)
Benefits paid	(125)	(122)
Benefit obligation at end of year	1,880	1,743	1,872
Other Benefits [Member]
Reconciliation of benefit obligation
Benefit obligation at beginning of year	431	524
Service cost	1	1	1
Interest cost	15	15	21
Actuarial loss (gain)	5	(57)
Benefits paid	(29)	(52)
Benefit obligation at end of year	$ 423	$ 431	$ 524