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Retirement Plans And Postretirement Benefits (Net Postretirement Benefit Costs And Postretirement Projected Benefit Obligation) (Details)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 3.20% 3.61%
Discount rate 3.61% 3.86%
Postretirement Costs    
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 4.80% 5.10%
Health care cost trend on covered charges, Initial 6.80% 6.67%
Health care cost trend on covered charges, Ultimate 5.96% 6.48%
Health care cost trend on covered charges, Years to ultimate 7 years 1 year
Post Retirement Benefit Obligations [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 5.07% 4.80%
Health care cost trend on covered charges, Initial 6.86% 6.80%
Health care cost trend on covered charges, Ultimate 6.23% 5.96%
Health care cost trend on covered charges, Years to ultimate 8 years 8 years