Summary Of Significant Accounting Policies (Other Income - Net) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Interest income	$ (2,587)	$ (2,710)	$ (2,162)
Interest on regulatory deferrals	(1,460)	(990)	(1,288)
Equity-related AFUDC	(6,585)	(6,554)	(6,669)
Non-service portion of pension and other postretirement benefit expenses	8,899	5,156	7,670
Net (income) loss on investments	(14,299)	5,369	4,160
Other expense (income)	1,104	1,187	(1,104)
Other income-net	$ (14,928)	$ 1,458	$ 607