Benefit Plans (Schedule Of Defined Benefit Plans Disclosures) (Details) - USD ($) $ in Thousands	3 Months Ended			6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net Unfunded Status of Plans [Roll Forward]
Net funded status before tax adjustments	$ (13,955)	$ (12,743)		$ (12,743)
Service cost	(1,852)	(1,853)	$ (2,113)	(3,705)	$ (4,226)
Interest cost	(6,836)	(6,836)	(6,305)	(13,672)	(12,610)
Expected return on assets	7,477	7,477	10,200	14,954	20,400
Net funded status before tax adjustments	(15,166)	(13,955)		(15,166)
Regulatory Assets Related to Pensions [Roll Forward]
Amortization of prior service cost	(957)		(960)	(1,913)	(1,919)
Defined Benefit Plan, Amortization of Gain (Loss)	(2,770)		(2,850)	(5,541)	(5,701)
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	197,725	201,452		201,452
Amortization of prior service cost	(957)	(956)
Regulatory assets before tax adjustments	193,998	197,725		$ 193,998
Defined Benefit Plan, Amortization of Gain (Loss)	$ (2,770)	$ (2,771)