Entity tax identification number Entity Tax Identification Number Maximum Maximum [Member] Legal Entity [Axis] Legal Entity [Axis] Statistical Measurement [Domain] Statistical Measurement [Domain] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Mutual funds Mutual Fund [Member] Total Fully Corrected Under VFCP and PTE 2002-51 EBP, Schedule of Delinquent Participant Contribution, Corrected Selling price EBP, Investment Sold, Excluding Plan Interest in Master Trust, Selling Price Employer contribution, fixed rate contribution, percentage EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage EBP, Employer Contribution, Annual Fixed Rate Contribution, Percentage EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Pretax, maximum annual compensation to total compensation, percentage EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Brokerage accounts EBP, Self-Directed Brokerage Account [Member] Total deductions from net assets EBP, Change in Net Asset Available for Benefit, Decrease Maximum borrowing, amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Minimum borrowing, amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount EBP, Employer Contribution, Matching Tranche [Domain] EBP, Employer Contribution, Matching Tranche [Domain] EBP, Employer Contribution, Matching Tranche [Domain] Investments, at fair value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Employee Bargaining Unit Type [Domain] Employee Bargaining Unit Type [Domain] Employee Bargaining Unit Type [Domain] Non-Bargaining Employee Non-Bargaining Employee [Member] Non-Bargaining Employee Level 1 Fair Value, Inputs, Level 1 [Member] Automatic deferral rate, annual increase EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate EBP, Participant Contribution, Automatic, Annual Increase Deferral Rate EBP, Investment, Fair Value and NAV [Abstract] Employer contribution, fixed rate contribution EBP, Employer Contribution, Annual Fixed Rate Contribution, Value EBP, Employer Contribution, Annual Fixed Rate Contribution, Value Total assets EBP, Asset Assets: EBP, Asset [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Additions to net assets: EBP, Change in Net Asset Available for Benefit, Increase [Abstract] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Payment of Benefits EBP, Payment to Participant [Policy Text Block] Amendment Flag Amendment Flag Participant elective and rollover EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution Basis of Accounting EBP, Basis of Accounting [Policy Text Block] EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] EBP, Description of Plan and Accounting Change [Abstract] Receivables: EBP, Receivable [Abstract] EBP, Investment, Fair Value and NAV EBP, Investment, Fair Value and NAV [Table Text Block] Investments [Domain] Investments [Domain] EBP, Schedule of Delinquent Participant Contribution [Abstract] Use of Estimates EBP, Use of Estimate [Policy Text Block] Maximum participant compensation matched EBP, Employer Contribution, Participant Compensation Matched, Maximum EBP, Employer Contribution, Participant Compensation Matched, Maximum Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Text Block] Cover [Abstract] Risks and Uncertainties EBP, Risk and Uncertainty [Text Block] Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash EBP, Schedule of Delinquent Participant Contribution [Line Items] EBP, Schedule of Delinquent Participant Contribution [Line Items] Investment, purchased, number of shares (in shares) EBP, Investment, Purchased, Number of Shares Minimum Minimum [Member] Investment Type [Axis] Investment Type [Axis] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Eligible Bargaining Unit Employees Eligible Bargaining Unit Employees [Member] Eligible Bargaining Unit Employees Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Interest and dividends EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Plan number EBP, Plan Number Maximum number of loans EBP, Note Receivable From Participant, Account, Maximum Number Of Loans EBP, Note Receivable From Participant, Account, Maximum Number Of Loans EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Description of the Plan EBP, Description of Plan [Text Block] Contributions Pending Correction in VFCP EBP, Schedule of Delinquent Participant Contribution, Pending Correction in VFCP EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] NW Natural Holding Company unitized stock EBP, Employer, Common Stock [Member] EBP, Schedule of Asset Held for Investment [Abstract] EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Total additions to net assets EBP, Change in Net Asset Available for Benefit, Increase SiEnergy Employees SiEnergy Employees [Member] SiEnergy Employees Investment income: EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Investment, Identifier [Axis] Investment, Identifier [Axis] Administrative fees and expenses EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Asset held for investment EBP, Asset Held for Investment Document Information [Line Items] Document Information [Line Items] Basis spread on variable rate EBP, Participant Loan, Basis Spread On Variable Rate EBP, Participant Loan, Basis Spread On Variable Rate EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Line Items] EBP, Risk and Uncertainty [Table] EBP, Risk and Uncertainty [Table] Participant compensation matched, percentage EBP, Employer Contribution, Participant Compensation Matched, Percentage EBP, Statement of Change in Net Asset Available for Benefit [Abstract] Level 2 Fair Value, Inputs, Level 2 [Member] Investment sold, number of shares (in shares) EBP, Investment, Sold, Number of Shares Maximum employer stock owned percentage EBP, Maximum Employer Stock Owned, Percent EBP, Maximum Employer Stock Owned, Percent Contributions Corrected Outside VFCP EBP, Schedule of Delinquent Participant Contribution, Corrected Outside VFCP EBP, Tax Status [Table] EBP, Tax Status [Table] Increase in net assets available for benefits EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Related Parties and Parties-In-Interest Transactions EBP, Related Party and Party-in-Interest Transactions [Text Block] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Total receivables EBP, Receivable Eligible Non-Bargaining Unit Employees Eligible Non-Bargaining Unit Employees [Member] Eligible Non-Bargaining Unit Employees Automatic deferral rate EBP, Participant Contribution, Automatic, Deferral Rate Investments, at fair value EBP, Investment, Fair Value [Abstract] Withdrawals and benefit payments EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Participant Contributions Transferred Late to Plan EBP, Schedule of Delinquent Participant Contribution, Transferred Late to Plan Total investments EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Statement of Net Asset Available for Benefit [Abstract] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Employer Contribution, Matching Trance One EBP, Employer Contribution, Matching Tranche One [Member] EBP, Employer Contribution, Matching Tranche One EBP, Tax Status [Abstract] Other liabilities EBP, Other Liability Participant administrative fee EBP. Administrative Fee, Participant EBP. Administrative Fee, Participant Participant loan fee EBP. Participant Loan Fee EBP. Participant Loan Fee Notes receivable from participants EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Administrative expense, gross EBP, Change In Net Asset Available For Benefit, Decrease From Administrative Expense, Gross EBP, Change In Net Asset Available For Benefit, Decrease From Administrative Expense, Gross Valuation of Investments & Investment Transactions and Net Investment Income Recognition EBP, Investment [Policy Text Block] Fair Value, Inputs, Level 1, Level 2, and Level 3 Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] Document Type Document Type EBP 008 EBP 008 [Member] EBP 008 Employee Bargaining Unit Type [Axis] Employee Bargaining Unit Type [Axis] Employee Bargaining Unit Type Termination Provisions EBP, Plan Termination [Text Block] Entity Central Index Key Entity Central Index Key Bargaining Employee Bargaining Employee [Member] Bargaining Employee Participant loan interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Common Collective Trust Common Collective Trust [Member] EBP, Risk and Uncertainty [Abstract] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Subsequent Event [Table] EBP, Subsequent Event [Table] Deductions from net assets: EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Forfeited nonvested account, decrease from employer contribution EBP, Forfeited Nonvested Account, Decrease from Employer Contribution Notes receivable from participants EBP, Note Receivable from Participant Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Vesting service period EBP, Employer Contribution Vesting Service Period EBP, Employer Contribution Vesting Service Period SIGNIFICANT ACCOUNTING POLICIES EBP, Summary of Accounting Policy [Text Block] Entity Registrant Name Entity Registrant Name Cost of asset EBP, Investment Acquired, Excluding Plan Interest in Master Trust, Cost EBP, Employer Contribution, Matching Tranche [Axis] EBP, Employer Contribution, Matching Tranche [Axis] EBP, Employer Contribution, Matching Tranche EBP, Subsequent Event [Abstract] Liabilities: EBP, Liability [Abstract] Subsequent Events EBP, Subsequent Event [Text Block] Form 5500, Schedule H, Line 4a; Schedule of Delinquent Participant Contributions EBP, Schedule of Delinquent Participant Contribution [Text Block] EBP, Schedule of Delinquent Participant Contribution [Table] EBP, Schedule of Delinquent Participant Contribution [Table] Income Tax Status EBP, Tax Status [Text Block] Maximum borrowing, to total account, percentage EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage EBP, Employer Contribution, Matching Trance Two EBP, Employer Contribution, Matching Tranche Two [Member] EBP, Employer Contribution, Matching Tranche Two EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] Document Information [Table] Document Information [Table] DELINQUENT CONTRIBUTIONS EBP, Delinquent Contributions [Text Block] EBP, Delinquent Contributions Notes Receivable from Participants EBP, Note Receivable from Participant [Policy Text Block] Net investment income EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Level 3 Fair Value, Inputs, Level 3 [Member] Contributions Not Corrected EBP, Schedule of Delinquent Participant Contribution, Not Corrected Net assets available for benefits Beginning of year End of year EBP, Net Asset Available for Benefit Entity [Domain] Entity [Domain] Maximum vesting age EBP, Employer Contribution Maximum Vesting Age EBP, Employer Contribution Maximum Vesting Age Contributions: EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Forfeited nonvested account EBP, Forfeited Nonvested Account Matching percentage EBP, Employer Contribution, Matching Percentage Vesting percentage EBP, Employer Contribution Vesting Percentage EBP, Employer Contribution Vesting Percentage NAV Fair Value Measured at Net Asset Value Per Share [Member] EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items]