Pension Plans And Other Postretirement Benefit Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Percentage of Net Periodic Benefit Costs Capitalized to Utility Property			40.00%
Percentage of Net Periodic Benefit Costs Recorded to Operating Expenses			60.00%
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 4,948	$ 5,450	$ 9,822	$ 10,900
Interest cost	7,100	6,466	14,238	12,932
Expected return on plan assets	(7,953)	(8,250)	(15,768)	(16,500)
Amortization of prior service cost	75	75	150	150
Net loss recognition	2,426	1,842	4,841	3,930
Net periodic benefit cost	6,596	5,583	13,283	11,412
Other Post-Retirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	753	804	1,525	1,608
Interest cost	1,164	1,197	2,536	2,394
Expected return on plan assets	(611)	(500)	(1,329)	(1,000)
Amortization of prior service cost	(275)	209	(550)	(606)
Net loss recognition	1,329	562	2,575	2,217
Net periodic benefit cost	$ 2,360	$ 2,272	$ 4,757	$ 4,613