Benefit Plans (Schedule Of Assumptions Used) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Assumptions used to determine benefit obligations: Discount rate	3.46%	3.89%	4.06%
Assumptions used to determine benefit obligations: Rate of compensation increase	4.00%	4.00%	4.00%
Assumptions used to determine net periodic benefit cost: Discount rate	3.89%	3.89%	3.72%
Assumptions used to determine net periodic benefit cost: Expected long-term return on plan assets	6.50%	6.50%	6.50%
Assumptions used to determine net periodic benefit cost: Rate of compensation increase	4.00%	4.00%	4.00%
Asset allocations as of measurement date:	100.00%	100.00%	100.00%
Value of shares (in thousands)			$ 68
Percent of total plan assets	0.00%	0.00%	0.40%
Cash and Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	2.00%	4.00%	8.00%
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	24.00%	33.00%	31.00%
Corporate Debt Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	18.00%	8.00%	7.00%
Municipal Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	38.00%	42.00%	43.00%
Investment Fund-Debt [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	9.00%	9.00%	8.00%
Insurance contracts [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	4.00%	3.00%	2.00%
Other Defined Benefit Plan Assets [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocations as of measurement date:	5.00%	1.00%	1.00%