Employee Benefit Plans (Schedule Of Amounts Recognized In Consolidated Balance Sheets) (Details) - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Change in Projected Benefit Obligation:
Projected benefit obligation at January 1	$ 533	$ 604
Interest cost	16	19
Actuarial loss	(21)	(7)
Participant contributions	13	15
Benefits paid	(91)	(98)
Projected benefit obligation at December 31	450	533
Change in fair value of plan assets:
Employer contributions	78	83
Participant contributions	13	15
Benefits paid	(91)	(98)
Funded status	(450)	(533)
Current liabilities	73	78
Noncurrent liabilities	377	455
Net amount recognized	450	533
Amount recognized in other comprehensive income (loss)
Unrecognized net actuarial gain
Total