Investment And Other Income, Net (Components Of Investment And Other Income, Net) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment And Other Income, Net [Abstract]
Interest and dividend income	$ 9	$ 6	$ 6
Pension and OPEB benefit (costs)	(42)	10	(2)
All other, net	(4)	(3)	(3)
Total investment and other income (loss), net	$ (37)	$ 13	$ 1

Amount of income (expense) related to nonoperating activities, classified as other.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.9)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Name:	us-gaap_OtherNonoperatingIncomeExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration