Postretirement Plans (Schedule Of Amounts Recognized In Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss/(gain)	$ 22,942	$ 22,802
Prior service (credits)	(1,211)	(1,243)
Total recognized in Accumulated other comprehensive loss	21,731	21,559
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss/(gain)	(59)	152
Prior service (credits)	(226)	(328)
Total recognized in Accumulated other comprehensive loss	$ (285)	$ (176)