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Pensions And Other Postretirement Benefits (Reconciliation Of Change In Fair Value Measurement Of Defined Benefit Plans' Consolidated Assets Using Significant Unobservable Inputs) (Details) - Level 3 [Member]
$ in Millions
12 Months Ended
Sep. 30, 2017
USD ($)
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]  
Beginning balance $ 28
Assets still held at reporting date 0
Assets sold during the period 0
Purchases, sales and settlements, net 0
Transfers in and/or out of Level 3 0
Ending balance 28
Insurance Contract [Member]  
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]  
Beginning balance 28
Assets still held at reporting date 0
Assets sold during the period 0
Purchases, sales and settlements, net 0
Transfers in and/or out of Level 3 0
Ending balance $ 28