XML 103 R62.htm IDEA: XBRL DOCUMENT v3.8.0.1
Summary Of Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]      
Unfunded benefit obligation for pensions and other postretirement benefit plans $ 8,090 $ 7,568  
Unfunded benefit obligation for pensions and other postretirement benefit plans, tax 4,356 4,075  
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]      
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]      
Amortization of net prior service cost (4,381) (1,171) $ 31
Amortization of net loss 36,833 (7,602) 2,623
Adjustment due to effects of regulation (b) (33,255) 7,360 (749)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, before Tax (803) (1,413) 1,905
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax 281 495 (667)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax $ (522) (918) $ 1,238
OREGON | Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]      
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]      
Adjustment due to effects of regulation (b)   $ 2,100