Pension Plans And Other Post-Retirement Benefits (Schedule Of Net Periodic Benefit Cost Not Yet Recognized) (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
Total recognized in regulatory assets	89,901	88,244
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	10,496	10,876
Prior service cost (credit)	(896)	(1,360)
Total recognized in regulatory assets	$ 9,600	$ 9,516