Employee Benefit Plans and Other Postretirement Benefits (Schedule Of-Weighted Average Health Care Cost Trend Rate Assumption) (Details) - Postretirement Health Coverage $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($)
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rate [Abstract]
Total of service and interest cost components, One Percent Increase	$ 648
Total of service and interest cost components, One Percent Decrease	(623)
Accumulated benefit obligation as of December 31, One Percent Increase	11,984
Accumulated benefit obligation as of December 31, One Percent Decrease	$ (10,940)