Investment And Other Income (Components Of Investment And Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Investment And Other Income [Abstract]
Interest and dividend income	$ 2	$ 2	$ 5	$ 5
Pension and OPEB benefit/(costs)	2	2	12	(1)
All other, net	(1)		(1)
Total investment and other income, net	$ 3	$ 4	$ 16	$ 4