Retirement Benefits (Schedule Of Assumptions Used) (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
DB Pension Plans
Weighted average for net periodic benefit cost
Expected long-term rate of return on plan assets	7.00%	7.00%	7.25%
Actual rate of return on plan assets	21.00%	(6.70%)	18.00%
DB SERP
Weighted average for benefit obligations
Discount rate	3.15%	4.32%	3.65%
Rate of compensation increase	5.50%	5.50%	5.50%
Weighted average for net periodic benefit cost
Service cost discount rate	4.58%	3.83%	4.51%
Interest cost discount rate	3.94%	3.26%	3.51%
Rate of compensation increase	5.50%	5.50%	5.50%
OPEB Plan
Weighted average for benefit obligations
Discount rate	3.32%	4.42%	3.74%
Weighted average for net periodic benefit cost
Service cost discount rate	4.63%	3.93%	4.89%
Interest cost discount rate	4.03%	3.35%	3.79%
Expected long-term rate of return on plan assets	7.00%	7.00%	7.25%
Pension Plan A | DB Pension Plans
Weighted average for benefit obligations
Discount rate	3.37%	4.48%	3.78%
Rate of compensation increase	3.50%	3.50%	3.50%
Weighted average for net periodic benefit cost
Service cost discount rate	4.55%	3.85%
Interest cost discount rate	4.08%	3.39%
Rate of compensation increase	3.50%	3.50%
Pension Plan B | DB Pension Plans
Weighted average for benefit obligations
Discount rate	3.17%	4.32%	3.64%
Weighted average for net periodic benefit cost
Service cost discount rate			4.53%
Interest cost discount rate	3.93%	3.24%	3.56%
Rate of compensation increase			3.60%