Pension Plans And Other Post-Retirement Benefits (Schedule Of Net Periodic Benefit Cost That Will Be Amortized) (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (87,786)	$ (85,510)
Prior service cost (credit)	2,115	2,734
Pension Benefits [Member] | Pension and Other Postretirement Plans Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(8,021)
Prior service cost (credit)	591
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(10,496)	(10,876)
Prior service cost (credit)	(896)	$ (1,360)
Other Postretirement Benefits [Member] | Pension and Other Postretirement Plans Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(531)
Prior service cost (credit)	$ (464)