Retirement Plans (Schedule Of Amounts Recognized In Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Non-current liability	$ (1,939)	$ (3,400)
Domestic Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current asset	0	0
Current liability	(30)	(40)
Non-current liability	(1,866)	(3,331)
Amounts recognized in the consolidated balance sheet	(1,896)	(3,371)
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Non-current asset	5	6
Current liability	(3)	(3)
Non-current liability	(73)	(69)
Amounts recognized in the consolidated balance sheet	$ (71)	$ (66)