Pension Plans And Other Postretirement Benefit Plans (Components Of Net Periodic Benefit Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Percentage of Net Periodic Benefit Costs Capitalized to Utility Property	40.00%
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax	$ (7,866)	$ (8,090)
Percentage of Net Periodic Benefit Costs Recorded to Operating Expenses	60.00%
Pension Plan And SERP [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax	$ 7,587	7,665
Service cost	21,614	20,406	$ 18,302
Interest cost	26,096	27,898	27,544
Expected return on plan assets	(33,018)	(31,626)	(27,547)
Amortization of prior service cost	257	2	2
Net loss recognition	7,879	9,793	8,511
Net periodic benefit cost	22,828	26,473	26,812
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), after Tax	279	425
Service cost	3,188	3,220	3,205
Interest cost	4,831	5,490	6,110
Expected return on plan assets	(1,973)	(1,899)	(1,861)
Amortization of prior service cost	(1,089)	(1,144)	(1,208)
Net loss recognition	4,232	4,934	5,728
Net periodic benefit cost	$ 9,189	$ 10,601	$ 11,974