Employee Benefit Plans and Other Postretirement Benefits (Schedule Of Assumptions Used To Determine Net Periodic Benefit Cost) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Pension and SERPA Benefits
Assumptions for benefit obligations:
Discount rate	3.71%	4.30%	4.53%
Rate of compensation	3.43%	3.50%	3.50%
Assumptions for net periodic benefit cost:
Discount rate	4.30%	4.53%	4.21%
Expected return on plan assets	7.25%	7.50%	7.75%
Rate of compensation increase	3.50%	3.50%	4.00%
Postretirement Health Coverage
Assumptions for benefit obligations:
Discount rate	3.52%	4.03%	4.29%
Assumptions for net periodic benefit cost:
Discount rate	4.03%	4.29%	3.99%
Expected return on plan assets	7.25%	7.50%	7.70%