Postretirement Plans (Schedule Of Assumptions Used To Calculate The Benefit Obligation) (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Expected return on plan assets	6.50%	6.80%	6.80%
Rate of compensation increase	4.30%	4.30%	5.30%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Interest Crediting Rates For Cash Balance Plans	5.00%	5.15%	5.15%
Pension Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.50%	3.30%	4.20%
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate	2.00%	3.00%	4.00%