Employee Benefit Plans (Schedule Of Amounts Recognized In Consolidated Balance Sheets) (Details) - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Change in Projected Benefit Obligation
Projected benefit obligation at January 1	$ 645	$ 588
Interest cost	27	25
Actuarial loss	24	134
Participant contributions	23	25
Benefits paid	(115)	(127)
Projected benefit obligation at December 31	604	645
Change in fair value of plan assets
Employer contributions	92	102
Participant contributions	23	25
Benefits paid	(115)	(127)
Funded status	(604)	(645)
Current liabilities	103	103
Noncurrent liabilities	501	542
Net amount recognized	604	645
Amount recognized in other comprehensive income
Unrecognized net actuarial gain
Total

Amount of gain (loss) related to change in benefit obligation resulting from changes in actuarial assumptions, for example, but not limited to, interest, mortality, employee turnover, salary, and temporary deviation from the substantive plan.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Gain or Loss
-URI http://asc.fasb.org/extlink&oid=49168827

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)(4)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920