Employee Benefit Plans (Schedule Of Allocation Of The Fair Value Of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	100.00%
Asset allocation value	$ 68,285	$ 59,416	$ 50,802
Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	100.00%	100.00%
Asset allocation value	$ 68,285	$ 59,416
Cash and Short-Term Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	5.00%
Cash and Short-Term Investments [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	18.00%	18.00%
Asset allocation value	$ 12,334	$ 10,624
Large Company Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	36.00%	34.00%
Asset allocation value	$ 24,790	$ 20,410
Mid Company Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	5.00%	7.00%
Asset allocation value	$ 3,595	$ 4,107
Small Company Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	5.00%	7.00%
Asset allocation value	$ 3,538	$ 4,071
International Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	15.00%
International Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	11.00%	11.00%
Asset allocation value	$ 7,502	$ 6,313
Fixed Income Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	15.00%	15.00%
Asset allocation value	$ 10,138	$ 9,106
Growth Funds [Member] | Quoted Prices In Active Markets For Identical Assets And Liabilities (Level 1) [Member]
Defined Benefit Plan Disclosure [Line Items]
Asset allocation percentage	10.00%	8.00%
Asset allocation value	$ 6,388	$ 4,785