v3.24.2.u1
Pension and Other Postretirement Benefit Costs - Amounts Recognized in Accumulated Other Comprehensive Loss - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2024
Jun. 30, 2023
Jun. 30, 2024
Jun. 30, 2023
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]        
Beginning balance     $ (7,049)  
Ending balance $ (6,500) $ (5,255) (6,500) $ (5,255)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Accumulated other comprehensive loss (6,500) (5,255) (6,500) (5,255)
Northwest Natural Gas Company [Member]        
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]        
Beginning balance     (7,237)  
Ending balance (7,092) (6,209) (7,092) (6,209)
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Accumulated other comprehensive loss (7,092) (6,209) (7,092) (6,209)
Non-Qualified Pension Plans, Defined Benefit | Northwest Natural Gas Company [Member]        
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]        
Beginning balance (7,359) (6,312) (7,237) (6,414)
Amortization of actuarial losses 207 140 380 279
Total reclassifications before tax 207 140 197 279
Tax expense (benefit) 60 (37) (52) (74)
Total reclassifications for the period 267 103 145 205
Ending balance (7,092) (6,209) (7,092) (6,209)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment to AOCI, before Tax 0 0 183 0
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Accumulated other comprehensive loss (7,092) (6,209) (7,092) (6,209)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment to AOCI, before Tax 0 0 183 0
Amortization of actuarial losses 207 140 380 279
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax 207 140 197 279
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax, Attributable to Parent (60) 37 52 74
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax $ 267 $ 103 $ 145 $ 205