Postretirement Plans (Schedule Of Amounts Recognized In Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ 22,802	$ 20,871
Prior service (credits)	(1,243)	(1,195)
Total recognized in Accumulated other comprehensive loss	21,559	19,676
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	152	781
Prior service (credits)	(328)	(397)
Total recognized in Accumulated other comprehensive loss	$ (176)	$ 384