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Retirement Benefits (Schedule Of Potential Changes In Key Assumptions) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2012
Pension Benefits [Member]
 
Defined Benefit Plan Disclosure [Line Items]  
Service Cost and Interest Cost, .25% decrease in discount rate $ (2)
Benefit Obligation, .25% decrease in discount rate 124
Service Cost and Interest Cost, .25% increase in salary rate 2
Benefit Obligation, .25% increase in salary rate 13
Postretirement Benefits [Member]
 
Defined Benefit Plan Disclosure [Line Items]  
Benefit Obligation, .25% decrease in discount rate 36
Service Cost and Interest Cost, 1.00% increase in annual medical trend 1
Benefit Obligation, 1.00% increase in annual medical trend 40
Service Cost and Interest Cost, 1.00% decrease in annual medical trend 0
Benefit Obligation, 1.00% decrease in annual medical trend $ (38)