Benefit Plans (Schedule Of Defined Benefit Plans Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net Unfunded Status of Plans [Roll Forward]
Net funded status before tax adjustments	$ (15,166)	$ (13,955)	$ (12,743)		$ (12,743)
Service cost	(1,853)	(1,852)	(1,853)	$ (2,112)	(5,558)	$ (6,338)
Interest cost	(6,836)	(6,836)	(6,836)	(6,305)	(20,508)	(18,915)
Expected return on assets	7,477	7,477	7,477	10,200	22,431	30,600
Net funded status before tax adjustments	(16,378)	(15,166)	(13,955)		(16,378)
Regulatory Assets Related to Pensions [Roll Forward]
Amortization of prior service cost	(956)			(959)	(2,869)	(2,878)
Defined Benefit Plan, Amortization of Gain (Loss)	(2,770)			(2,851)	(8,311)	(8,552)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	0			$ 0	0	$ 1,230
Pension Plan [Member]
Regulatory Assets Related to Pensions [Roll Forward]
Regulatory assets before tax adjustments	193,998	197,725	201,452		201,452
Amortization of prior service cost	(956)	(957)	(956)
Regulatory assets before tax adjustments	190,272	193,998	197,725		$ 190,272
Defined Benefit Plan, Amortization of Gain (Loss)	$ (2,770)	$ (2,770)	$ (2,771)