Postretirement Plans (Schedule Of Estimated Amount That Will Be Amortized From Accumulated Other Comprehensive Loss Into Net Periodic Benefit Cost) (Details) $ in Millions	12 Months Ended
Dec. 31, 2016 USD ($)
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Recognized net actuarial loss	$ 801
Amortization of prior service (credits)	(41)
Total	760
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Recognized net actuarial loss	10
Amortization of prior service (credits)	(137)
Total	$ (127)

Amount included in accumulated other comprehensive income (AOCI) expected to be recognized as components of net periodic benefit cost for the fiscal year that follows the most recent annual statement of financial position, including gain (loss), prior service cost (credit), and transition asset (obligation).

No definition available.

Name:	us-gaap_DefinedBenefitPlanAmountToBeAmortizedFromAccumulatedOtherComprehensiveIncomeLossNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration