Summary of Significant Accounting Policies (Schedule Of Items Reclassified Out Of AOCI And The Corresponding Location And Impact On The Consolidated Statements Of Income) (Details) - Reclassification out of Accumulated Other Comprehensive Income [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Defined benefit pension plan adjustments	$ 1,897	$ 1,745
Income tax benefit	(779)	(646)
Net of tax	$ 1,118	$ 1,099