Pension and Other Post-Employment Benefits (Weighted Average Assumptions Used In Determining Net Periodic Pension And Other Post-Retirement Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Long-Term Rate of Return on Plan Assets	4.25%
Pension Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.50%	3.75%	3.75%
Long-Term Rate of Return on Plan Assets	5.25%	6.25%	6.25%
Rates of Increase in Compensation Levels	3.49%	3.49%	3.99%
OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.76%	4.05%	3.66%
Rates of Increase in Compensation Levels	6.10%	6.43%	6.47%