Employee Benefit Plans (Schedule Of Assumptions Used To Develop The Actuarial Present Value Of The Benefit Obligations) (Details)	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Retirement Benefits [Abstract]
Discount rate	2.32%	3.09%	4.12%
Salary scale increases	3.50%	3.50%	3.50%
Interest credit rate for cash balance plan	4.50%	4.50%	4.50%