Employee Benefits And Deferred Compensation Plans (Schedule Of Net Periodic Benefit Costs, SERP) (Details) - Supplemental Executive Retirement Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 168	$ 188	$ 194
Interest cost	137	144	146
Net amortization and deferral	112	167	161
Net periodic benefit cost	$ 417	$ 499	$ 501