Retirement Plans (Schedule Of Fair Value Of Plan Assets) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 55,624	$ 60,536	$ 54,332	$ 50,021
Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	55,487	60,419
Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	117
Cash Equivalents [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	117
Cash Equivalents [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	117
Vanguard Prime Money Market Mutual Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	117
Vanguard Prime Money Market Mutual Fund [Member] | Level 2 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	137	117
Equity Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,052	12,137
Equity Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	10,052	12,137
Vanguard Total Stock Market Index Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,513	6,658
Vanguard Total Stock Market Index Fund [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	5,513	6,658
Vanguard Total International Stock Index Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,539	5,479
Vanguard Total International Stock Index Fund [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	4,539	5,479
Fixed Income Mutual Funds [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	45,435	48,282
Fixed Income Mutual Funds [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	45,435	48,282
Vanguard Long-Term Investment Grade Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27,260	29,065
Vanguard Long-Term Investment Grade Fund [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	27,260	29,065
Vanguard Long-Term Bond Index Fund [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	18,175	19,217
Vanguard Long-Term Bond Index Fund [Member] | Level 1 [Member]
Defined Benefit Plan Disclosure [Line Items]
Fair value of plan assets	$ 18,175	$ 19,217