Summary Of Significant Accounting Policies (Reclassifications Out of Accumulated Other Comprehensive Loss) (Details) - Reclassification Out of Accumulated Other Comprehensive Income [Member] - Accumulated Defined Benefit Plans Adjustment [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Amortization of net prior service cost	$ (300)	$ (312)	$ (898)	$ (934)
Amortization of net loss	3,637	3,642	10,913	10,926
Adjustment due to effects of regulation	(3,057)	(3,115)	(9,172)	(11,453)
Total before tax	280	215	843	(1,461)
Tax benefit (expense)	(98)	(75)	(295)	512
Net of tax	$ 182	$ 140	$ 548	(949)
OREGON
Reclassification Out of Accumulated Other Comprehensive Income [Line Items]
Adjustment due to effects of regulation				$ 2,100