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Retirement Plans And Postretirement Benefits (Net Postretirement Benefit Costs And Postretirement Projected Benefit Obligation) (Details)
 5 Months Ended 12 Months Ended
Dec. 31, 2015
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]      
Discount rate   3.71% 3.20%
Discount rate   3.20% 3.61%
Postretirement Benefit Obligations [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Discount rate   5.57% 5.07%
Health care cost trend on covered charges, Initial   6.53% 6.86%
Health care cost trend on covered charges, Ultimate   6.05% 6.23%
Health care cost trend on covered charges, Years to ultimate 8 years   8 years
Postretirement Benefit Costs [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   7 years 7 years