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Benefit Plans (Assumptions to Determine Postretirement Benefit Obligations) (Details)
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]    
Health care cost trend rate assumed for next year 6.50% 7.00%
Ultimate trend rate 5.00% 5.00%
Year that the rate reaches the ultimate trend rate 2025 2022
Pension [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 4.40% 3.70%
Rate of compensation increase 4.00% 4.00%
Postretirement Benefit Plan [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Discount rate 4.40% 3.70%
Rate of compensation increase 0.00% 0.00%