Employee Benefit Plans (Schedule Of Amounts Recognized In Consolidated Balance Sheets) (Details) - Postretirement Medical Benefits [Member] - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Change in Projected Benefit Obligation:
Projected benefit obligation at January 1	$ 450	$ 533
Interest cost	16	16
Actuarial loss	63	(21)
Participant contributions	10	13
Benefits paid	(86)	(91)
Projected benefit obligation at December 31	453	450
Change in fair value of plan assets:
Employer contributions	76	78
Participant contributions	10	13
Benefits paid	(86)	(91)
Funded status	(453)	(450)
Current liabilities	71	73
Noncurrent liabilities	382	377
Net amount recognized	453	450
Amount recognized in other comprehensive income (loss)
Unrecognized net actuarial gain
Total

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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Amount of contribution received by defined benefit plan from employer which increases plan assets.

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Amount of funded (unfunded) status of defined benefit plan, measured as difference between fair value of plan assets and benefit obligation. Includes, but is not limited to, overfunded (underfunded) status.

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Amount of cost recognized for passage of time related to defined benefit plan.

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Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans.

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