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Pension and Other Postretirement Benefits Costs - Schedule of Future Employer Contributions and Benefit Payments (Details) - Northwest Natural Gas Company [Member] - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Dec. 31, 2019
Dec. 22, 2013
Defined Benefit Plan Disclosure [Line Items]        
Payment for Pension and Other Postretirement Benefits $ 9,600      
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Defined Contribution Plan, Cost 8,800 $ 8,300 $ 7,000  
Western States Office and Professional Employees Union Pension Fund [Member]        
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Multiemployer Plan, Employer Contribution, Cost 400 $ 700 $ 600  
Multiemployer Plan, Pension, Insignificant, Plan Contribution 600      
Multiemployer Plans, Withdrawal Obligation 5,800     $ 8,300
Western States Office and Professional Employees Union Pension Fund [Member] | Maximum [Member]        
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Multiemployer Plan, Pension, Insignificant, Employer Contribution under Collective-Bargaining Arrangement to All Participating Employer Contributions, Percentage   5.00% 5.00%  
Western States Office and Professional Employees Union Pension Fund [Member] | Minimum [Member]        
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Multiemployer Plan, Pension, Insignificant, Employer Contribution under Collective-Bargaining Arrangement to All Participating Employer Contributions, Percentage   6.00% 6.00%  
Pension Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Payment for Pension and Other Postretirement Benefits 11,944 $ 31,362    
Expected future employer contributions 2,335      
Benefits paid 25,371 25,073 $ 23,160  
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Year 1 23,210      
Year 2 24,020      
Year 3 24,728      
Year 4 25,325      
Year 6 25,824      
Thereafter 133,617      
Other Postretirement Benefits Plan [Member]        
Defined Benefit Plan Disclosure [Line Items]        
Payment for Pension and Other Postretirement Benefits 2,050 1,837    
Expected future employer contributions 1,654      
Benefits paid 2,050 $ 1,837 $ 1,774  
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]        
Year 1 1,654      
Year 2 1,665      
Year 3 1,654      
Year 4 1,643      
Year 6 1,606      
Thereafter $ 7,640