Trading Arrangements, by Individual
Trading Arrangements, by Individual [Table]
Gas costs
Asset Recoverable Gas Costs [Member]
Trading Arrangement:
Trading Arrangement [Axis]
Maximum
Maximum [Member]
Year 2
Year Two [Member]
Year Two
Title of 12(b) Security
Title of 12(b) Security
Weighted average interest rate (as percent)
Debt, Weighted Average Interest Rate
Adjustment to Compensation, Amount
Adjustment to Compensation Amount
Target hedge achieved
Target Hedge Achieved
Target Hedge Achieved
Segment Reporting [Abstract]
Segment Reporting [Abstract]
Pension and Other Postretirement Benefit Costs
Retirement Benefits [Text Block]
Cap Amount
Guarantor Obligations, Maximum Exposure, Undiscounted
Gas reserves
Oil And Gas, Gas Reserves, Value
Oil And Gas, Gas Reserves, Value
Derivative Instrument [Axis]
Derivative Instrument [Axis]
Schedule of Public Utility Property, Plant, and Equipment
Public Utility Property, Plant, and Equipment [Table Text Block]
Junior Subordinated Debt
Junior Subordinated Debt [Member]
Consolidated Entities [Axis]
Consolidated Entities [Axis]
Entity Common Stock, Shares Outstanding
Entity Common Stock, Shares Outstanding
Property, plant and equipment
Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment
Gasco Upland Site
Gasco Upland Site [Member]
Gasco Upland Site
Amortization
Amortization
Physical
Physical [Member]
Physical [Member]
Leases [Abstract]
Leases [Abstract]
Other comprehensive income (loss):
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Non-current assets
Business Combination, Recognized Asset Acquired, Asset, Noncurrent
NWN Water
Northwest Natural Water Company [Member]
Northwest Natural Water Company
Consolidated Entities [Domain]
Consolidated Entities [Domain]
Reclassification out of Accumulated Other Comprehensive Income
Reclassification out of Accumulated Other Comprehensive Income [Member]
Gas storage revenue, net
Gas Storage Revenue, Net of Regulatory Sharing [Member]
Gas Storage Revenue, Net of Regulatory Sharing [Member]
Outstanding Aggregate Erroneous Compensation Amount
Outstanding Aggregate Erroneous Compensation Amount
Collaborative Arrangement and Arrangement Other than Collaborative [Domain]
Collaborative Arrangement and Arrangement Other than Collaborative [Domain]
Number of reportable segments
Number of Reportable Segments
Total current liabilities
Liabilities, Current
Income (loss) before income taxes
Income (Loss) Attributable to Parent, before Tax
Lessee, operating lease, maximum term of short-term leases not recorded on the balance sheet
Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet
Lessee, Operating Lease, Maximum Term of Short-term Leases not recorded on the Balance Sheet
Environmental Remediation Obligations [Abstract]
Environmental Remediation Obligations [Abstract]
General taxes
Taxes, Miscellaneous
Depreciation study
Public Utilities, Requested Rate Depreciation, Amount
Public Utilities, Requested Rate Depreciation, Amount
Regulated gas storage
Regulated Operating Revenue, Gas
Derivative instruments
Derivative Liability, Current
SiEnergy And Pines
SiEnergy And Pines [Member]
SiEnergy And Pines
Entity Address, City or Town
Entity Address, City or Town
Derivative, fair value, net
Derivative, Fair Value, Net
Number of RSUs granted in period (in shares)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period
Number of amended complaints filed
Number Of Amended Complaints Filed
Number Of Amended Complaints Filed
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Statement of Financial Position [Abstract]
Statement of Financial Position [Abstract]
Peer Group Total Shareholder Return Amount
Peer Group Total Shareholder Return Amount
Amount allocated to construction
Defined Benefit Plan Amount Allocated To Construction
Net periodic benefit cost allocated to construction.
Residual value of leased asset
Residual Value of Leased Asset
Total Shareholder Return Vs Peer Group
Total Shareholder Return Vs Peer Group [Text Block]
Non-Rule 10b5-1 Arrangement Terminated
Non-Rule 10b5-1 Arrangement Terminated [Flag]
Qualified defined benefit pension plan expense
Pension Cost (Reversal of Cost)
Parent Company
Parent Company [Member]
Schedule of Long-term Debt Instruments [Table]
Schedule of Long-Term Debt Instruments [Table]
Environmental costs
Environmental Restoration Costs [Member]
Gasco Uplands
Gasco Uplands [Member]
Gasco Uplands [Member]
Natural first mortgage bonds
Natural First Mortgage Bonds [Member]
Natural First Mortgage Bonds
Segment Reporting
Segment Reporting [Table Text Block]
Schedule of Regulatory Liabilities
Schedule of Regulatory Liabilities [Table Text Block]
Derivative credit risk valuation adjustment, derivative liabilities
Derivative Credit Risk Valuation Adjustment, Derivative Liabilities
Current liabilities
Business Combination, Recognized Liability Assumed, Liability, Current
Document Period End Date
Document Period End Date
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Accumulated Other Comprehensive Income Loss Net Of Tax [Roll Forward]
Accumulated Other Comprehensive Income Loss Net Of Tax
Subsidiaries
Subsidiaries [Member]
Lessor, Operating Leases
Lessor, Operating Leases [Text Block]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
Reclassification out of Accumulated Other Comprehensive Income [Domain]
Lessee, Lease, Description [Line Items]
Lessee, Lease, Description [Line Items]
Year two
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two
Accumulated other comprehensive loss
Accumulated Other Comprehensive Income (Loss), Net of Tax
Entity Shell Company
Entity Shell Company
Consolidation Items [Domain]
Consolidation Items [Domain]
Other, net
Effective Income Tax Rate Reconciliation, Other Adjustments, Amount
Operating lease liabilities
Operating Lease, Liability, Current
Schedule of Accounts Receivable, Allowance for Credit Loss
Accounts Receivable, Allowance for Credit Loss [Table Text Block]
Mortgages
Mortgages [Member]
Earnings Per Share
Earnings Per Share [Text Block]
Earnings (loss) per share of common stock:
Earnings Per Share [Abstract]
Document Fiscal Period Focus
Document Fiscal Period Focus
Total lease revenue
Lease Income
Peer Group Issuers, Footnote
Peer Group Issuers, Footnote [Text Block]
Trading Symbol
Trading Symbol
Asset optimization revenue sharing
Asset Optimization Revenue Sharing [Member]
Asset Optimization Revenue Sharing
Capital expenditures
Payments to Acquire Property, Plant, and Equipment
Taxes accrued
Accrued Income Taxes, Current
Schedule of Business Combination, Recognized Asset Acquired and Liability Assumed
Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block]
Company Selected Measure Name
Company Selected Measure Name
Incremental cost or benefit to collect or refund to customers
Incremental Cost or Benefit to Collect or Refund to Customers
Incremental Cost or Benefit to Collect or Refund to Customers
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Abstract]
Total reclassifications before tax
Reclassification from AOCI, Current Period, before Tax, Attributable to Parent
Derivative, fixed interest rate
Derivative, Fixed Interest Rate
Earnings (loss) per share of common stock:
Earnings Per Share, Diluted [Abstract]
Regulated Operation, Regulatory Asset [Table]
Regulated Operation, Regulatory Asset [Table]
Sale of stock, commissions and fees paid
Sale of Stock, Commissions and Fees Paid
Sale of Stock, Commissions and Fees Paid
Cumulative proceeds received on all transactions
Cumulative Proceeds Received On All Transactions
Cumulative amount of cash and other consideration received in exchange for shares or stock issued or sold. Include amounts of cash received, fair value of non-cash assets received, fair value of liabilities assumed, and fair value of any other forms of consideration.
Credit Facility [Domain]
Credit Facility [Domain]
Depreciation
Depreciation, Depletion and Amortization, Nonproduction
Receivables from affiliates
Other Receivables, Net, Current
Dividends per share of common stock (in dollars per share)
Common Stock, Dividends, Per Share, Cash Paid
Equity Valuation Assumption Difference, Footnote
Equity Valuation Assumption Difference, Footnote [Text Block]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred income taxes
Deferred Income Taxes and Tax Credits
Collaborative Arrangement and Arrangement Other than Collaborative [Axis]
Collaborative Arrangement and Arrangement Other than Collaborative [Axis]
Business combination, goodwill, expected tax deductible, amount
Business Combination, Goodwill, Expected Tax Deductible, Amount
Term (in years)
Unrecorded Unconditional Purchase Obligation, Term
Non-Qualified Pension Plans, Defined Benefit
Non-Qualified Pension Plans, Defined Benefit [Member]
Non-Qualified Pension Plans, Defined Benefit
Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table]
Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table]
NW Natural margin
Gross Profit
Lessor, sales-type lease, term of contract
Lessor, Sales-type Lease, Term of Contract
Other, net
Increase (Decrease) in Other Operating Assets and Liabilities, Net
Operating cash flows from operating leases
Operating Lease, Payments
Award Timing Predetermined
Award Timing Predetermined [Flag]
Adjustment To PEO Compensation, Footnote
Adjustment To PEO Compensation, Footnote [Text Block]
Derivative instruments
Derivative Asset, Noncurrent
Effective income tax rate
Effective Income Tax Rate Reconciliation, Percent
Gasco Upland site
Gasco/Siltronic Upland [Member]
Discloses the details related to the Gasco environmental site
Additional shares for stock-based compensation plans
Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements
Remediation non-recovery Percentage
Remediation Non-Recovery Percentage
Remediation Non-Recovery Percentage
Inventory, emissions allowances
Inventory, Emissions Allowances
Inventory, Emissions Allowances
Lessor, sales-type lease, renewal term
Lessor, Sales-type Lease, Renewal Term
Depreciation
Depreciation
Plan Name [Domain]
Plan Name [Domain]
Scenario [Domain]
Scenario [Domain]
Operating lease right of use asset, net
Operating Lease, Right-of-Use Asset
Increase (decrease) in RNG Facility prepaid operating assets
Increase (Decrease) In RNG Facility Prepaid Operating Assets
Increase (Decrease) In RNG Facility Prepaid Operating Assets
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Debt Instrument, Name [Domain]
Debt Instrument, Name [Domain]
ATM Equity Program
ATM Equity Program [Member]
At-the-market equity program.
Cash dividend payments on common stock
Payments of Ordinary Dividends, Common Stock
Expiration Date
Trading Arrangement Expiration Date
(Decrease) increase in cash, cash equivalents and restricted cash
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation
Inline Utilities, LLC
Inline Utilities, LLC [Member]
Inline Utilities, LLC
Gasco Uplands IRAM
Gasco Uplands IRAM [Member]
Gasco Uplands IRAM
Beginning balance
Ending balance
Equity, Including Portion Attributable to Noncontrolling Interest
SiEnergy
SiEnergy [Member]
SiEnergy
Deferred environmental expenditures, net
Other Increase (Decrease) in Environmental Liabilities
Plant in service
Building and Building Improvements [Member]
Aggregate Pension Adjustments Service Cost
Aggregate Pension Adjustments Service Cost [Member]
Derivative [Table]
Derivative [Table]
Proceeds from common stock issued, net
Proceeds from Issuance of Common Stock
Receivables, net
Increase (Decrease) in Accounts and Other Receivables
Par value (in dollars per share)
Common Stock, No Par Value
Net income (loss)
Business Combination, Pro Forma Information, Pro Forma Income (Loss), after Tax
Schedule of Environmental Loss Contingencies by Site
Schedule of Environmental Loss Contingencies by Site [Table Text Block]
Asset optimization revenue sharing
Increase (Decrease) in Asset Optimization Revenue Sharing
Increase (Decrease) in Asset Optimization Revenue Sharing
Unrecognized compensation costs
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount
Segments [Domain]
Segments [Domain]
Debt
Debt Disclosure [Text Block]
Scenario [Axis]
Scenario [Axis]
Pension balancing
Pension Costs [Member]
Business Combination [Table]
Business Combination [Table]
PEO Actually Paid Compensation Amount
PEO Actually Paid Compensation Amount
Secured Debt
Secured Debt [Member]
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Site Contingency [Table]
Site Contingency [Table]
Gas Year 2025 - 2026
Gas Year 2025 - 2026 [Member]
Gas Year 2025 - 2026
Purchase of equity method investment
Payments to Acquire Equity Method Investments
Stated interest rate (as percent)
Debt Instrument, Interest Rate, Stated Percentage
Dividends on common stock
Dividends, Common Stock, Cash
Total equity
Beginning balance
Ending balance
Equity, Attributable to Parent
Assets:
Assets [Abstract]
Insider Trading Policies and Procedures [Line Items]
Allowance for uncollectible accounts
Accounts Receivable, Allowance for Credit Loss, Current
Performance Shares
Performance Shares [Member]
Regulatory assets
Regulatory assets, current
Current regulatory assets
Regulatory Asset, Current
Accounts payable, related party [Extensible Enumeration]
Accounts Payable, Related Party [Extensible Enumeration]
Interest expense, net
Interest expense, net
Interest Income (Expense), Nonoperating
Investments in gas reserves, non-current
Inventory, Gas in Storage Underground, Noncurrent
Antidilutive shares (in shares)
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount
Entity Central Index Key
Entity Central Index Key
Regulatory Liabilities [Line Items]
Regulatory Liability [Line Items]
Less: Accumulated depreciation
Less: Accumulated depreciation
Property, Plant, and Equipment, Accumulated Depreciation, Depletion, and Amortization
Equity [Abstract]
Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year
Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member]
Income tax at statutory rate (federal)
Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount
Total NW Holdings
NW Holdings
Northwest Holdings [Member]
Northwest Holdings [Member]
Investment, Name [Axis]
Investment, Name [Axis]
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract]
Market equity program equity available for issuance
At the Market Equity Program, Available for Issuance
At the Market Equity Program, Available for Issuance
Accumulated Other Comprehensive Income (Loss)
AOCI Attributable to Parent [Member]
All Individuals
All Individuals [Member]
Thereafter
Unrecorded Unconditional Purchase Obligation, To Be Paid, After Year Four
Unrecorded Unconditional Purchase Obligation, To Be Paid, After Year Four
Pension and other postretirement benefit liabilities
Pension and Other Postretirement Plans Costs [Member]
Regulatory Liability [Domain]
Regulatory Liability [Domain]
Undiscounted monitoring costs (in years)
Environmental Exit Costs, Anticipated Cost, Period
Environmental Exit Costs, Anticipated Cost, Period
Total non-current assets
Assets, Noncurrent
Statement [Line Items]
Statement [Line Items]
Total assets
Assets
Industry Sector [Axis]
Industry Sector [Axis]
Gas reserves, current
Deferred Gas Cost
Operating Segments
Operating Segments [Member]
Stock-Based Compensation
Share-Based Payment Arrangement [Text Block]
EPA final feasibility study and proposed remediation plan, clean-up costs, portland harbor
Proposed Remediation Plan, Clean-Up Costs
Proposed Remediation Plan, Clean-Up Costs
PEO
PEO [Member]
Other non-current liabilities
Other Liabilities, Noncurrent
CCI credits liability
CCI Credits Liability
CCI Credits Liability
Goodwill
Goodwill
Retirement Plan Type [Axis]
Retirement Plan Type [Axis]
Forgone Recovery due to Violation of Home Country Law, Amount
Forgone Recovery due to Violation of Home Country Law, Amount
Retained Earnings
Retained Earnings [Member]
Operating lease liabilities
Operating Lease, Liability, Noncurrent
Total operating expenses
Operating Expenses
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent
Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member]
Shares outstanding (in shares)
Common Stock, Shares, Outstanding
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Award Timing Disclosures [Line Items]
Diluted (in dollars per share)
Earnings Per Share, Diluted
Schedule of Incremental Revenue
Public Utilities General Disclosures [Table Text Block]
Equity method investment, number of customer connections
Equity Method Investment, Number of Customer Connections
Equity Method Investment, Number of Customer Connections
Weather Adjusted Rate Mechanism
Weather Adjusted Rate Mechanism [Member]
Weather Adjusted Rate Mechanism
CCI deferred costs
CCI Deferred Costs
CCI Deferred Costs
Litigation Case [Domain]
Litigation Case [Domain]
Differences required to be flowed-through by regulatory commissions
Other Tax Expense (Benefit), Differences To Be Flowed-Through By Regulatory Commissions
Other Tax Expense (Benefit), Differences To Be Flowed-Through By Regulatory Commissions
Total identifiable net assets
Business Combination, Recognized Asset Acquired, Asset
Equity method investment, difference between carrying amount and underlying equity
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity
NWN Water Term Loan Due 2026
NWN Water Term Loan Due 2026 [Member]
NWN Water Term Loan Due 2026
Share-based Payment Arrangement [Abstract]
Share-Based Payment Arrangement [Abstract]
Tax benefit
Reclassification from AOCI, Current Period, Tax
Series B Senior Notes
Secured Senior B Notes [Member]
Secured Senior B Notes
Schedule of Investment
Investment [Table Text Block]
Amortization of non-qualified employee benefit plan liability, net of taxes $33 and $25 for the three months ended and $66 and $50 for the six months ended June 30, 2026 and 2025, respectively
Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax
Equity Awards Adjustments, Footnote
Equity Awards Adjustments, Footnote [Text Block]
Number of shares granted (in shares)
Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted
Environmental exit costs, anticipated cost
Environmental Exit Costs, Anticipated Cost
NWN Water unsecured senior notes
NWN Water Unsecured Senior Notes [Member]
NWN Water Unsecured Senior Notes
Gas appliance retail revenue
Gas Appliance Center Revenue [Member]
Gas Appliance Center Revenue
Construction work in progress
Construction in Progress [Member]
State income tax
Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount
Equity Method Investment [Table]
Equity Method Investment [Table]
Industrial demand side management
Industrial demand side management [Member]
Industrial demand side management
Revenue taxes
Excise Taxes
The amount of excise taxes collected by a public utility, which are deducted as a cost of sales.
Weighted average interest rate (as percent)
Long-Term Debt, Weighted Average Interest Rate, at Point in Time
Operating activities:
Cash Provided by (Used in) Operating Activity, Continuing Operation [Abstract]
Capital structure, long term debt
Public Utilities, Approved Debt Capital Structure, Percentage
Unrealized gain (loss) on interest rate swaps, net of taxes $(4) and $— for the three months ended and $(10) and $47 for the six months ended June 30, 2026 and 2025, respectively
Derivative, Gain (Loss) on Derivative, Net
Income from operations
Income (loss) from operations
NW Natural income from operations
Operating Income (Loss)
Revenue, remaining performance obligation, amount
Revenue, Remaining Performance Obligation, Amount
Business Combinations
Business Combination [Text Block]
Rule 10b5-1 Arrangement Adopted
Rule 10b5-1 Arrangement Adopted [Flag]
Service cost
Defined Benefit Plan, Service Cost
Site contingency number of management pieces
Site Contingency, Number Of Management Pieces
Site Contingency, Number Of Management Pieces
Trustee council members - number of claimants
Trustee Council Members - Number of Claimants
Trustee Council Members - Number of Claimants
Yakama Nation
Yakama Nation [Member]
Yakama Nation [Member]
Restricted Cash and Cash Equivalent Item [Line Items]
Restricted Cash and Cash Equivalent Item [Line Items]
Shares issued (in shares)
Common Stock, Shares, Issued
Distribution revenues
Regulated Operating Revenue
Amortization of non-qualified employee benefit plan liability, tax
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax
Other receivable, after allowance for credit loss, related party [Extensible Enumeration]
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration]
Product and Service [Domain]
Product and Service [Domain]
Class of Stock [Line Items]
Class of Stock [Line Items]
Disaggregation of Revenue [Table]
Disaggregation of Revenue [Table]
Equity:
Capitalization, Long-Term Debt and Equity [Abstract]
Acquiree's earnings since acquisition date, actual
Business Combination, Acquiree's Earnings (Loss) since Acquisition Date, Actual
Deferred tax liabilities
Deferred Income Tax Liabilities, Net
Compensation Actually Paid vs. Other Measure
Compensation Actually Paid vs. Other Measure [Text Block]
Employer contributions
Defined Contribution Plan, Cost
Termination Date
Trading Arrangement Termination Date
Subsequent Events [Abstract]
Derivative, loss on derivative
Derivative, Loss on Derivative
Compensation Actually Paid vs. Total Shareholder Return
Compensation Actually Paid vs. Total Shareholder Return [Text Block]
Other
NW Natural Other [Member]
NW Natural Other [Member]
Other current liabilities
Other Liabilities, Current
Derivative instruments
Derivative Asset, Current
Northwest Holdings and Northwest Natural
Northwest Holdings and Northwest Natural [Member]
Northwest Holdings and Northwest Natural [Member]
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)
Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]
Fair Value as of Grant Date
Award Grant Date Fair Value
Pay vs Performance Disclosure, Table
Pay vs Performance [Table Text Block]
Operations and maintenance
Operating Costs and Expenses
Arrangement Duration
Trading Arrangement Duration
Consolidation Items [Axis]
Consolidation Items [Axis]
Entity Address, Postal Zip Code
Entity Address, Postal Zip Code
Entity Registrant Name
Entity Registrant Name
Number of remediation projects
Site Contingency, Number Of Remediation Projects
Site Contingency, Number Of Remediation Projects
Insider Trading Policies and Procedures Not Adopted
Insider Trading Policies and Procedures Not Adopted [Text Block]
Operating revenues
Total operating revenues
Revenues
Revenues
Forgone Recovery due to Expense of Enforcement, Amount
Forgone Recovery due to Expense of Enforcement, Amount
Term Loan
Term Loan [Member]
Term Loan
Net periodic benefit cost charged to expense
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense
Defined Benefit Plan Net Periodic Benefit Cost Charged To Expense
Award vesting period
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period
Award Type [Domain]
Award Type [Domain]
Annual insurance proceeds to apply against remediation costs
Annual Insurance Proceeds To Apply Against Remediation Costs
Annual Insurance Proceeds To Apply Against Remediation Costs
Lessee, operating lease, term of contract
Lessee, Operating Lease, Term of Contract
Total cumulative gas reserves investment
Total Cumulative Gas Reserves Investment
Total cumulative gas reserves investment
Geographical [Axis]
Geographical [Axis]
Deferred credits and other non-current liabilities:
Deferred Credits and Other Liabilities [Abstract]
Schedule of Short-term Debt [Table]
Short-Term Debt [Table]
Washington Climate Commitment Act Allowances
Washington Climate Commitment Act Allowances [Member]
Washington Climate Commitment Act Allowances
Legal Entity [Axis]
Legal Entity [Axis]
Equity method investment, number of employees
Equity Method Investment, Number of Employees
Equity Method Investment, Number of Employees
Lessee, Lease, Description [Table]
Lessee, Lease, Description [Table]
Cash, cash equivalents and restricted cash, beginning of period
Cash, cash equivalents and restricted cash, end of period
Cash, cash equivalents and restricted cash
Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Non-NEOs
Non-NEOs [Member]
Inventories
Public Utilities, Inventory
Ownership percentage of Avion
Equity Method Investment, Ownership Percentage
Schedule of Debt
Schedule of Debt [Table Text Block]
Derivative liability
Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral
Investment, Name [Domain]
Investment, Name [Domain]
Leases
Lessee, Operating Leases [Text Block]
Long-Term Debt, Type [Domain]
Long-Term Debt, Type [Domain]
Regulated Operation, Regulatory Liability [Table]
Regulated Operation, Regulatory Liability [Table]
Statistical Measurement [Axis]
Statistical Measurement [Axis]
Schedule of Income Statement Presentation of Derivative Instruments
Derivative Instruments, Gain (Loss) [Table Text Block]
Deferred taxes related to gas reserves
Deferred Taxes Related To Gas Reserves
Deferred taxes related to gas reserves
Award Type [Axis]
Award Type [Axis]
Unrealized loss on derivatives
Deferred Derivative Gain (Loss)
Amounts deferred to regulatory accounts on balance sheet
Deferred Derivative Gain (Loss) [Member]
Short-term lease expense
Short-Term Lease, Cost (Benefit)
Short-Term Lease, Cost (Benefit)
Named Executive Officers, Footnote
Named Executive Officers, Footnote [Text Block]
Gas Year [Domain]
Gas Year [Domain]
[Domain] for Gas Year [Axis]
Retained earnings
Retained Earnings (Accumulated Deficit)
Product and Service [Axis]
Product and Service [Axis]
Awards Close in Time to MNPI Disclosures
Awards Close in Time to MNPI Disclosures [Table]
Pension Benefits
Pension Plan [Member]
Short-term Debt [Line Items]
Short-Term Debt [Line Items]
Schedule of Operating Lease, Weighted Average Remaining Term and Discount Rates
Operating Lease, Weighted Average Remaining Term And Discount Rates [Table Text Block]
Operating Lease, Weighted Average Remaining Term and Discount Rates [Table Text Block]
Schedule of Lease Revenue
Operating Lease, Lease Income [Table Text Block]
Operating lease expense
Operating Lease, Cost
Year one
Unrecorded Unconditional Purchase Obligation, to be Paid, Year One
Derivative Contract [Domain]
Derivative Contract [Domain]
Investment in unconsolidated affiliates
Equity Method Investment, Aggregate Cost
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Cloud-based software
Increase (Decrease) in Cloud-based software Operating Assets
Amount of increase (decrease) in Cloud-based software Operating Assets.
Number of businesses acquired
Business Combination, Number of Businesses Acquired
Total liabilities and equity
Liabilities and Equity
Employee Stock Option
Share-Based Payment Arrangement, Option [Member]
Investments in life insurance policies
Life Insurance, Corporate or Bank Owned, Amount
Segments [Axis]
Segments [Axis]
Additional 402(v) Disclosure
Additional 402(v) Disclosure [Text Block]
Asset Class [Axis]
Asset Class [Axis]
Tabular List, Table
Tabular List [Table Text Block]
Name
Awards Close in Time to MNPI Disclosures, Individual Name
Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested
Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member]
Non-current assets:
Assets, Noncurrent [Abstract]
Operations and maintenance
Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses
Long-Lived Asset, Class [Domain]
Long-Lived Asset, Class [Domain]
Property, Plant, and Equipment [Table]
Property, Plant, and Equipment [Table]
NW Holdings Unsecured Senior Bonds
NW Holdings Unsecured Senior Bonds [Member]
NW Holdings Unsecured Senior Bonds
Adjustment to Compensation:
Adjustment to Compensation [Axis]
Amortization of regulatory balancing account
Amortization Of Regulatory Balancing Account
Amortization Of Regulatory Balancing Account
Rule 10b5-1 Arrangement Terminated
Rule 10b5-1 Arrangement Terminated [Flag]
Aggregate Erroneous Compensation Amount
Aggregate Erroneous Compensation Amount
Interest paid, net of capitalization
Interest Paid, Excluding Capitalized Interest, Operating Activity
Schedule of NWN Gas Utility Margin
NWN Gas Utility Margin [Table Text Block]
Tabular disclosure of the components of the margin in the Utility segment.
Credit Facility [Axis]
Credit Facility [Axis]
Name
Measure Name
Pay vs Performance Disclosure [Line Items]
Debt Instrument [Line Items]
Debt Instrument [Line Items]
Goodwill, impairment loss
Goodwill, Impairment Loss
Other
Other Regulatory Assets (Liabilities) [Member]
Security and systems improvements
Security and systems improvements [Member]
Security and systems improvements
Assets under sales-type leases
Net Investment in Lease, before Allowance for Credit Loss, Noncurrent
Name
Trading Arrangement, Individual Name
Cash and cash equivalents
Cash and Cash Equivalent
Overall Rate of Return
Public Utilities, Requested Rate Increase (Decrease), Percentage
Company Selected Measure Amount
Company Selected Measure Amount
Business combination, communities of business acquired
Business Combination, Communities Of Business Acquired
Business Combination, Communities Of Business Acquired
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Line Items]
North Mist Lease
North Mist Lease [Member]
North Mist Lease [Member]
Weighted-average remaining lease term (years)
Operating Lease, Weighted Average Remaining Lease Term
Non-PEO NEO
Non-PEO NEO [Member]
Schedule Of Investments In Unconsolidated Affiliates
Schedule Of Investments In Unconsolidated Affiliates [Table Text Block]
Schedule Of Investments In Unconsolidated Affiliates
Other - NW Holdings
Other Northwest Holdings [Member]
Other Northwest Holdings [Member]
Award Timing Method
Award Timing Method [Text Block]
Forecast
Forecast [Member]
Forgone Recovery, Explanation of Impracticability
Forgone Recovery, Explanation of Impracticability [Text Block]
2025-2027 Award
2025-2027 Award [Member]
2025-2027 Award
Amortization of net actuarial loss
Defined Benefit Plan, Amortization of Gain (Loss)
Net income (loss)
Net income (loss)
Net income
Net Income (Loss) Attributable to Parent
Long-Term Debt, Type [Axis]
Long-Term Debt, Type [Axis]
Erroneous Compensation Analysis
Erroneous Compensation Analysis [Text Block]
Location, Statement of Financial Position, Balance [Axis]
Location, Statement of Financial Position, Balance [Axis]
Environmental Remediation Site [Domain]
Environmental Remediation Site [Domain]
Return on Equity
Public Utilities, Approved Return on Equity, Percentage
Restatement Determination Date:
Restatement Determination Date [Axis]
Number of potentially responsible parties (more than)
Site Contingency, Number Of Potentially Responsible Parties
Site Contingency, Number Of Potentially Responsible Parties
Operating revenues [Abstract]
Revenues [Abstract]
Additional collateral, aggregate fair value
Collateral Already Posted, Aggregate Fair Value
Pension Benefits Adjustments, Footnote
Pension Benefits Adjustments, Footnote [Text Block]
Average common shares outstanding:
Weighted Average Number of Shares Outstanding, Diluted [Abstract]
Statutory tax rate
Business Combination, Pro Forma Information, Tax Rate For Adjustments
Business Combination, Pro Forma Information, Tax Rate For Adjustments
Statistical Measurement [Domain]
Statistical Measurement [Domain]
Document Fiscal Year Focus
Document Fiscal Year Focus
Business combination, acquisition cost
Business Combination, Acquisition-Related Cost, Expense
Revenue, remaining performance obligation, expected timing of satisfaction, year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period
Site contingency, environmental remediation costs recognized
Environmental Exit Costs, Costs Accrued to Date
Series A Senior Notes
Secured Senior A Notes [Member]
Secured Senior A Notes
Common stock - no par value; authorized 100,000,000 shares; issued and outstanding 42,093,292, 40,909,610, and 41,563,577 at June 30, 2026 and 2025, and December 31, 2025, respectively
Common Stock, Value, Issued
Shares withheld for tax purposes
Payment, Tax Withholding, Share-Based Payment Arrangement
Schedule of Long-Term Debt Instruments
Schedule of Long-Term Debt Instruments [Table Text Block]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]
Number of net investments in sales-type leases
Number of Net Investments in Sales-Type Leases
Number of Net Investments in Sales-Type Leases
Transferred over Time
Transferred over Time [Member]
Line of Credit
Line of Credit [Member]
Restatement Determination Date
Restatement Determination Date
Tax Jurisdiction of Domicile [Extensible Enumeration]
Tax Jurisdiction of Domicile [Extensible Enumeration]
Expected return on plan assets
Defined Benefit Plan, Expected Return (Loss) on Plan Assets
Schedule of Effective Income Tax Rate Reconciliation
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]
Beginning Balance
Ending Balance
Accounts Receivable, Allowance for Credit Loss
Regulatory liabilities
Regulatory liability, noncurrent
Regulatory Liability, Noncurrent
Percentage of clean-up costs
Proposed Remediation Plan, Percentage of Clean-Up Costs
Proposed Remediation Plan, Percentage of Clean-Up Costs
Amendment Flag
Amendment Flag
NWN Gas Utility
NWN Gas Utility [Member]
NWN Gas Utility [Member]
Current liabilities:
Liabilities, Current [Abstract]
Total annual remediation expense and interest
Total Annual Remediation Expense And Interest
Total Annual Remediation Expense And Interest
Schedule of Notional Amounts of Outstanding Derivative Positions
Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block]
Investments
Investment [Text Block]
Timing of Transfer of Good or Service [Domain]
Timing of Transfer of Good or Service [Domain]
Payables to affiliates
Accounts Payable, Other, Current
Adjustment to Non-PEO NEO Compensation Footnote
Adjustment to Non-PEO NEO Compensation Footnote [Text Block]
Collateral Posted with NW Natural Counterparties
Collateral Posted with NW Natural Counterparties [Member]
Collateral Posted with NW Natural Counterparties
Property, Plant, and Equipment [Abstract]
Property, Plant, and Equipment [Abstract]
Entity Address, State or Province
Entity Address, State or Province
Schedule of SiEnergy Gas Utility Margin
SiEnergy Gas Utility Margin [Table Text Block]
SiEnergy Gas Utility Margin
PEO Total Compensation Amount
PEO Total Compensation Amount
Capital expenditures
Segment Reporting, Long-Lived Asset, Expenditure for Addition
Foreign exchange
Derivative, Notional Amount
Basic (in shares)
Average common shares outstanding - basic (in shares)
Weighted Average Number of Shares Outstanding, Basic
Regulatory assets
Regulatory assets, noncurrent
Long-term regulatory assets
Regulatory Asset, Noncurrent
Proceeds from other operating activity
Proceeds from Other Operating Activity
Regulatory Liability [Axis]
Regulatory Liability [Axis]
SiEnergy Credit Agreement Loans
SiEnergy Holdings Credit Agreement [Member]
SiEnergy Holdings Credit Agreement
Investments [Abstract]
Investments [Abstract]
Revenue from contract with customer, including assessed tax
Revenue from Contract with Customer, Including Assessed Tax
Schedule of Cash Flow, Supplemental Disclosures
Schedule of Cash Flow, Supplemental Disclosures [Table Text Block]
Recognized amounts of identifiable assets acquired and liabilities assumed:
Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill, Less Noncontrolling Interest [Abstract]
Amount
Equity Method Investment, Additional Underlying Equity in Net Assets
Equity Method Investment, Additional Underlying Equity in Net Assets
ROIC performance period (in years)
Share-Based Compensation Arrangements By Share-Based Payment Award, Performance Metric, ROIC, Period
Share-Based Compensation Arrangements By Share-Based Payment Award, Performance Metric, ROIC, Period
Fair value of consideration transferred:
Business Combination, Consideration Transferred [Abstract]
Document Information [Line Items]
Document Information [Line Items]
Award Timing MNPI Disclosure
Award Timing MNPI Disclosure [Text Block]
Other Portland Harbor
Portland Harbor Other [Member]
Discloses the details related to the Portland Harbor Other environmental site
NW Natural
NW Natural
NW Natural [Member]
NW Natural
Natural gas (in therms)
Derivative, Nonmonetary Notional Amount
Deferred gas costs
Increase (Decrease) in Deferred Gas Cost
Line of credit facility, maximum borrowing capacity
Line of Credit Facility, Maximum Borrowing Capacity
Collaborative Arrangement and Arrangement Other than Collaborative [Table]
Collaborative Arrangement and Arrangement Other than Collaborative [Table]
Current maturities of long-term debt
Long-Term Debt, Current Maturities
Environmental remediation
Environmental remediation expense
Environmental Remediation Expense, before Recovery
Accrued site liabilities
Regulatory Assets, Environmental Regulatory Accrued Site Liabilities
Regulatory Assets, Environmental Regulatory Accrued Site Liabilities
New Accounting Standards
New Accounting Pronouncements, Policy [Policy Text Block]
Litigation Case [Axis]
Litigation Case [Axis]
Unsecured Debt
Unsecured Debt [Member]
Non-current liabilities
Business Combination, Recognized Liability Assumed, Liability, Noncurrent
Natural gas sales
Natural Gas Sales [Member]
Natural Gas Sales [Member]
Shares issued pursuant to equity based plans, net of shares withheld for taxes
Stock Issued During Period, Value, Equity Based Plan, Net Of Shares Withheld ForTaxes
Stock Issued During Period, Value, Equity Based Plan, Net of Shares Withheld for Taxes.
Intangible asset, excluding goodwill
Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Excluding Goodwill
Long-term debt
Long-term debt
Long-Term Debt
Property, Plant and Equipment
Property, Plant, and Equipment [Text Block]
Changes in assets and liabilities:
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract]
NRD liability claim yakama nation
NRD Liability Claim Yakama Nation
NRD Liability Claim Yakama Nation
Cash used by investing activities
Cash Provided by (Used in) Investing Activity, Including Discontinued Operation
Equity Awards Adjustments, Excluding Value Reported in Compensation Table
Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member]
Total regulatory asset deferral
Regulatory Asset
Additional studies and design costs
Cost Incurred, Studies And Design Costs
Cost Incurred, Studies And Design Costs
Common Stock
Equity [Text Block]
Security Exchange Name
Security Exchange Name
Total deferred credits and other non-current liabilities
Deferred Credits and Other Liabilities, Noncurrent
Contributions to qualified defined benefit pension plans
Payment for Pension Benefits
Accrued unbilled and other
Accrued unbilled and other [Member]
Accrued unbilled and other [Member]
Interest accrued
Interest Payable, Current
Name
Outstanding Recovery, Individual Name
AOCI, cash flow hedge, cumulative gain (Loss), after tax
AOCI, Cash Flow Hedge, Cumulative Gain (Loss), after Tax
SiEnergy term loan
Delayed Draw Term Loan Facility [Member]
Delayed Draw Term Loan Facility
Award Timing, How MNPI Considered
Award Timing, How MNPI Considered [Text Block]
Long-term debt, current maturities
Long-term debt, Current Maturities, Gross
Long-term debt, Current Maturities, Gross
Series F Notes
Series F Notes [Member]
Series F Notes
Geographical [Domain]
Geographical [Domain]
Industry Regulation
Public Utilities, Policy [Policy Text Block]
Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year
Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member]
Oregon
OREGON
Pension Adjustments Prior Service Cost
Pension Adjustments Prior Service Cost [Member]
Revenue Requirement Increase
Public Utilities, Approved Rate Increase (Decrease), Amount
Total reclassifications for the period
Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent
Year three
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three
Award Date [Axis]
Award Date [Axis]
Other investments
Total other investments
Other Long-Term Investments
Balance Outstanding
Gross long-term debt
Long-Term Debt, Gross
Asset Class [Domain]
Asset Class [Domain]
Avion Water
Avion Water [Member]
Avion Water
Compensation Amount
Outstanding Recovery Compensation Amount
Individual:
Individual [Axis]
Outstanding interest acquired, percentage
Business Combination, Voting Equity Interest Acquired, Percentage
Right of use assets obtained in exchange for lease obligations
Right Of Use Assets Obtained In Exchange For Lease Obligations [Abstract]
Right Of Use Assets Obtained In Exchange For Lease Obligations
Diluted (in shares)
Average common shares outstanding - diluted (in shares)
Weighted Average Number of Shares Outstanding, Diluted
Disaggregation of Revenue [Line Items]
Disaggregation of Revenue [Line Items]
Entity Emerging Growth Company
Entity Emerging Growth Company
Income taxes
Deferred Income Tax Charge [Member]
Pension and other postretirement benefit liabilities
Liability, Defined Benefit Plan, Noncurrent
Underlying Security Market Price Change
Underlying Security Market Price Change, Percent
Annual tariff rider collection
Annual Tariff Rider Collection
Annual Tariff rider collection
Commercial Paper
Commercial Paper [Member]
Derivative Instruments
Derivative Instruments and Hedging Activities Disclosure [Text Block]
Regulatory Asset [Axis]
Regulatory Asset [Axis]
Award Date [Domain]
Award Date [Domain]
Money market funds, at carrying value
Cash Equivalent, Money Market Fund, Carrying Value
Short-term debt
Balance Outstanding
Short-Term Debt
Revenue from Contract with Customer [Abstract]
Revenue from Contract with Customer [Abstract]
SiEnergy secured senior notes
SiEnergy Secured Senior Notes [Member]
SiEnergy Secured Senior Notes
Restricted cash included in other current assets
Restricted Cash, Current
Oregon Steel Mills
Oregon Steel Mills [Member]
Discloses the details related to Oregon Steel Mills.
Asset optimization revenue sharing bill credits
Asset optimization revenue sharing bill credits
Asset optimization revenue sharing bill credits
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Other Commitments
Other Commitments [Table Text Block]
Leasing revenue
Leasing revenue [Member]
Leasing revenue [Member]
Weighted-average grant date fair value (in dollars per share)
Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value
All Executive Categories
All Executive Categories [Member]
WASHINGTON
WASHINGTON
Pension Adjustments Service Cost
Pension Adjustments Service Cost [Member]
Unrealized loss on derivative, tax
Unrealized Gain (Loss) on Derivative, tax
Unrealized Gain (Loss) on Derivative, tax
Schedule of Net Benefit Costs
Schedule of Net Benefit Costs [Table Text Block]
Schedule of EPS Calculation
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]
Debt Disclosure [Abstract]
Debt Disclosure [Abstract]
Segment Information
Segment Reporting [Text Block]
Minimum
Minimum [Member]
Industrial
Industrial [Member]
Industrial [Member]
Schedule of Disaggregation of Revenue
Disaggregation of Revenue [Table Text Block]
Sales-type leases
Sales-type Lease, Lease Income
Location, Statement of Income, Balance [Axis]
Location, Statement of Income, Balance [Axis]
Customers of business acquired
Business Combination, Customers of Business Acquired
Business Combination, Customers Of Business Acquired
Non-Rule 10b5-1 Arrangement Adopted
Non-Rule 10b5-1 Arrangement Adopted [Flag]
Public Utilities, Regulatory Proceeding [Domain]
Public Utilities, Regulatory Proceeding [Domain]
Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table
Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member]
Timing of Transfer of Good or Service [Axis]
Timing of Transfer of Good or Service [Axis]
Accrued unbilled revenue
Unbilled Receivables, Current
Increase of last rate case
Public Utilities, Requested Rate Increase (Decrease), Amount
Consideration transferred
Business Combination, Consideration Transferred, Liabilities Incurred
Business Combination [Line Items]
Business Combination [Line Items]
Net periodic benefit cost
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)
Issuance of common stock, net of issuance costs
Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs
Shares authorized (in shares)
Common Stock, Shares Authorized
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]
Exercise Price
Award Exercise Price
Schedule of Equity Method Investments [Line Items]
Schedule of Equity Method Investments [Line Items]
Enrolled customers during time period (in years)
Contingency, Enrolled Customers During Time Period, Period
Contingency, Enrolled Customers During Time Period, Period
Segment Reporting [Line Items]
Segment Reporting [Line Items]
Document Quarterly Report
Document Quarterly Report
Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested
Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member]
NW Natural
Northwest Natural Gas Company [Member]
Northwest Natural Gas Company [Member]
Common Stock
Common Stock Including Additional Paid in Capital [Member]
Long-term debt retired
Repayments of Long-Term Debt
Awards Close in Time to MNPI Disclosures, Table
Awards Close in Time to MNPI Disclosures [Table Text Block]
Equity Component [Domain]
Equity Component [Domain]
Foreign Exchange
Foreign Exchange Contract [Member]
Contract with customer, refund liability
Contract with Customer, Refund Liability
Gas Year [Axis]
Gas Year [Axis]
Gas Year [Axis]
Accounts receivable
Accounts Receivable, before Allowance for Credit Loss, Current
Adoption Date
Trading Arrangement Adoption Date
Scenario, Plan
Scenario, Plan [Member]
Income and other taxes
Increase (Decrease) in Accrued Taxes Payable
Environmental Matters
Environmental Loss Contingency Disclosure [Text Block]
Title
Trading Arrangement, Individual Title
Forgone Recovery due to Disqualification of Tax Benefits, Amount
Forgone Recovery due to Disqualification of Tax Benefits, Amount
Accounting Policies [Abstract]
Accounting Policies [Abstract]
Restatement does not require Recovery
Restatement Does Not Require Recovery [Text Block]
Environmental Remediation Site [Axis]
Environmental Remediation Site [Axis]
Other
Proceeds from (Payment for) Other Financing Activity
Insider Trading Policies and Procedures Adopted
Insider Trading Policies and Procedures Adopted [Flag]
Insurance proceeds and interest
Environmental Regulatory Insurance Proceeds And Interest
Environmental Regulatory Insurance Proceeds And Interest
Decoupling
Decoupling [Member]
Decoupling [Member]
Business Combination [Domain]
Business Combination [Domain]
Commitments and Contingencies
Commitments and Contingencies Disclosure [Text Block]
Compensation Actually Paid vs. Net Income
Compensation Actually Paid vs. Net Income [Text Block]
Operating leases
Operating Lease, Lease Income
Restricted Stock Units (RSUs)
Restricted Stock Units (RSUs) [Member]
Guarantor obligations, percent of contracted therms
Guarantor Obligations, Percent Of Contracted Therms
Guarantor Obligations, Percent Of Contracted Therms
Underlying Asset Class [Axis]
Underlying Asset Class [Axis]
All Adjustments to Compensation
All Adjustments to Compensation [Member]
Corporate Nonsegment
Segment Reporting, Reconciling Item, Corporate Nonsegment [Member]
Business Combination [Axis]
Business Combination [Axis]
Cash provided by operating activities
Cash Provided by (Used in) Operating Activity, Including Discontinued Operation
Natural Gas Therms
Natural Gas Therms [Member]
Natural Gas Therms [Member]
Income Statement [Abstract]
Income Statement [Abstract]
Document Transition Report
Document Transition Report
Operating expenses:
Operating Expenses [Abstract]
Stock Appreciation Rights (SARs)
Stock Appreciation Rights (SARs) [Member]
Other Immaterial Leases
Other Immaterial Leases [Member]
Other Immaterial Leases
City Area Code
City Area Code
Document Information [Table]
Document Information [Table]
Subsequent Events
Subsequent Events [Text Block]
Estimated fair value
Debt Instrument, Fair Value Disclosure
Name
Forgone Recovery, Individual Name
Non-GAAP Measure Description
Non-GAAP Measure Description [Text Block]
Entity [Domain]
Entity [Domain]
Increase (decrease) in cloud-based software capital expenditure
Increase (Decrease) in Cloud-based software Capital Expenditure
Increase (Decrease) in Cloud-based software Capital Expenditure
Current Liabilities
Accrued Environmental Loss Contingencies, Current
Share based compensation award target share (in shares)
Share Based Compensation Award Target Share
The target number of shares to be awarded under the plan if performance goals are achieved.
Stock issued during period, shares, new issues
Stock Issued During Period, Shares, New Issues
Share-based payment arrangement, expense
Share-Based Payment Arrangement, Expense
Erroneously Awarded Compensation Recovery
Erroneously Awarded Compensation Recovery [Table]
Entity Current Reporting Status
Entity Current Reporting Status
Cash (used by) provided by financing activities
Cash Provided by (Used in) Financing Activity, Including Discontinued Operation
Total Shareholder Return Amount
Total Shareholder Return Amount
NWN Water
NWN Water [Member]
NWN Water
Water and wastewater revenue
Water and wastewater revenue [Member]
Water and wastewater revenue
Commercial
Commercial [Member]
Commercial [Member]
Schedule of Business Combination, Pro Forma Information
Business Combination, Pro Forma Information [Table Text Block]
Adjustments to reconcile net income to cash provided by operations:
Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract]
Write-offs recognized, net of recoveries
Accounts Receivable, Allowance for Credit Loss, Writeoff
Year 1
Year One [Member]
Year One
Total property, plant, and equipment, net
Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization
Portland Harbor
Portland Harbor [Member]
Portland Harbor [Member]
Interest cost
Defined Benefit Plan, Interest Cost
Other revenue
Regulated Operating Revenue, Other
Regulatory Assets [Line Items]
Regulatory Asset [Line Items]
2024-2026 Award
2024-2026 Award [Member]
2024-2026 Award
Variable lease, payment
Variable Lease, Payment
Provision recorded, net of adjustments
Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease)
Underlying Securities
Award Underlying Securities Amount
Revenue
Revenue from Contract with Customer [Text Block]
Front Street site
Front Street [Member]
Discloses the details related to the Front Street environmental site
Alternative revenue
Alternative revenue [Member]
Alternative revenue [Member]
Residential
Residential [Member]
Residential [Member]
Other insignificant acquisitions
Other insignificant acquisitions [Member]
Other Insignificant acquisitions [Member]
2026-2028 Award
2026-2028 Award [Member]
2026-2028 Award
Other
Payment for (Proceeds from) Other Investing Activity
Inventories
Increase (Decrease) in Inventories
Weighted-average discount rate
Operating Lease, Weighted Average Discount Rate, Percent
Segment Reporting [Table]
Segment Reporting [Table]
Gasco Sediments
Gasco Siltronic Sediments [Member]
Discloses the details related to the Gasco Siltronic Sediments environmental site
Decoupling mechanism
Change In Decoupling Regulatory Deferral
Change In Decoupling Regulatory Deferral
Acquiree's revenue since acquisition date, actual
Business Combination, Acquiree's Revenue since Acquisition Date, Actual
Investing activities:
Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract]
Schedule of Lease Expense
Lease, Cost [Table Text Block]
Other current assets
Other Assets, Current
Commitments and Contingencies Disclosure [Abstract]
All Trading Arrangements
All Trading Arrangements [Member]
Other Performance Measure, Amount
Other Performance Measure, Amount
Award Timing MNPI Considered
Award Timing MNPI Considered [Flag]
Current Fiscal Year End Date
Current Fiscal Year End Date
Non-PEO NEO Average Total Compensation Amount
Non-PEO NEO Average Total Compensation Amount
Derivative [Line Items]
Derivative [Line Items]
Derivative asset, fair value, amount not off set against collateral
Derivative Asset, Subject to Master Netting Arrangement, before Offset of Collateral
Unrecorded unconditional purchase obligation, including lease not yet commenced, to be paid, total amount
Unrecorded Unconditional Purchase Obligation
Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year
Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member]
Entity File Number
Entity File Number
Changes in other short-term debt, net
Proceeds from (Repayments of) Short-Term Debt
Stock-based compensation
Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture
Capitalized computer software, amortization
Capitalized Cost, Software to be Sold, Leased, or Marketed, Amortization Expense
Recovery of Erroneously Awarded Compensation Disclosure [Line Items]
Measure:
Measure [Axis]
Asset management revenue, net
Asset Management Revenue, Net of Regulatory Sharing [Member]
Asset Management Revenue, Net of Regulatory Sharing [Member]
Non-Current Liabilities
Accrued Environmental Loss Contingencies, Noncurrent
Current assets
Business Combination, Recognized Asset Acquired, Asset, Current
Equity Components [Axis]
Equity Components [Axis]
Other operating expenses
Other Cost and Expense, Operating
Document and Entity Information [Abstract]
Document and Entity Information [Abstract]
General document and entity information
Other revenue
Other revenue [Member]
Other revenue [Member]
Income taxes paid, net of refunds
Income Tax Paid, after Refund Received
Regulatory accounts
Increase (Decrease) in Regulatory Assets and Liabilities
Entity Interactive Data Current
Entity Interactive Data Current
NWN Water Utility
NWN Water Utility [Member]
NWN Water Utility
Capital contribution from parent
Cash contributions received from parent
Proceeds from Contributions from Parent
Entity Small Business
Entity Small Business
Comprehensive income (loss)
Other comprehensive income
Comprehensive Income (Loss), Net of Tax, Attributable to Parent
Number of production facilities
Commitments And Contingencies, Number Of Production Facilities
Commitments And Contingencies, Number Of Production Facilities
Property, Plant, and Equipment [Line Items]
Property, Plant, and Equipment [Line Items]
MNPI Disclosure Timed for Compensation Value
MNPI Disclosure Timed for Compensation Value [Flag]
Equity method investment, underlying equity in net assets
Equity Method Investment, Underlying Equity in Net Assets
Other non-current assets
Other Assets, Noncurrent
Sale of stock, consideration received on transaction
Sale of Stock, Consideration Received
Sale of Stock, Consideration Received
Financing activities:
Cash Provided by (Used in) Financing Activity, Continuing Operation [Abstract]
Document Type
Document Type
Acquisitions, net of cash acquired
Payments to Acquire Businesses, Net of Cash Acquired
Significant Accounting Policies
Significant Accounting Policies [Text Block]
Site Contingency [Line Items]
Site Contingency [Line Items]
SiEnergy
SiEnergy Gas Utility [Member]
SiEnergy Gas Utility
Other
Other [Member]
Other
Subsequent Event [Line Items]
Subsequent Event [Line Items]
Statement of Stockholders' Equity [Abstract]
Statement of Stockholders' Equity [Abstract]
Pines Holdings, Inc.
Pines [Member]
Pines
Long-term debt issued
Proceeds from Issuance of Long-Term Debt
Local Phone Number
Local Phone Number
Other Postretirement Benefits
Other Postretirement Benefits Plan [Member]
Sales-type lease, net investment in lease, allowance for credit loss
Sales-type Lease, Net Investment in Lease, Allowance for Credit Loss
Restrictions on Cash and Cash Equivalents [Table]
Restrictions on Cash and Cash Equivalents [Table]
Cost of Long-Term Debt
Public Utilities, Requested Debt Capital Structure, Percentage
Capital structure, common equity
Public Utilities, Approved Equity Capital Structure, Percentage
Commitments and contingencies (Note 16)
Commitments and Contingencies
Year 3
Year Three [Member]
Year Three
Property, plant, and equipment
Property, Plant, and Equipment, before Accumulated Depreciation, Depletion, and Amortization
Changed Peer Group, Footnote
Changed Peer Group, Footnote [Text Block]
Reclassification out of Accumulated Other Comprehensive Income [Axis]
Reclassification out of Accumulated Other Comprehensive Income [Axis]
SiEnergy other
SiEnergy Other [Member]
SiEnergy Other
Executive Category:
Executive Category [Axis]
Transferred at Point in Time
Transferred at Point in Time [Member]
Liabilities and equity:
Liabilities and Equity [Abstract]
Other Commitments [Table]
Other Commitments [Table]
Non-PEO NEO Average Compensation Actually Paid Amount
Non-PEO NEO Average Compensation Actually Paid Amount
Other comprehensive income (loss), cash flow hedge, gain (loss), reclassification, after tax
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax
Supplemental disclosure of cash flow information:
Supplemental Cash Flow Information [Abstract]
Cost of gas
Less: Cost of gas
Utilities Operating Expense, Gas and Petroleum Purchased
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table]
PEO Name
PEO Name
Cumulative EBITDA performance period (in years)
Share-Based Compensation Arrangements By Share-Based Payment Award, Performance Metric, Cumulative EBITDA, Period
Share-Based Compensation Arrangements By Share-Based Payment Award, Performance Metric, Cumulative EBITDA, Period
Long-Lived Asset, Class [Axis]
Long-Lived Asset, Class [Axis]
Stock Price or TSR Estimation Method
Stock Price or TSR Estimation Method [Text Block]
Entity Tax Identification Number
Entity Tax Identification Number
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Prepaid expense
Prepaid Expense and Other Assets
Other Commitments [Line Items]
Other Commitments [Line Items]
Accounts payable
Increase (Decrease) in Accounts Payable
Entity Incorporation, State or Country Code
Entity Incorporation, State or Country Code
Aggregate Erroneous Compensation Not Yet Determined
Aggregate Erroneous Compensation Not Yet Determined [Text Block]
Material Terms of Trading Arrangement
Material Terms of Trading Arrangement [Text Block]
Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year
Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member]
Organization and Principles of Consolidation
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]
Debt Instrument [Axis]
Debt Instrument [Axis]
Subsequent Event [Table]
Subsequent Event [Table]
Renewable natural gas sales
Renewable Natural Gas Sales [Member]
Renewable Natural Gas Sales
Revenue taxes
Utilities Operating Expense, Taxes
Public Utilities, Regulatory Proceeding [Axis]
Public Utilities, Regulatory Proceeding [Axis]
Financial
Financial [Member]
Financial [Member]
Basic (in dollars per share)
Earnings Per Share, Basic
Total current assets
Assets, Current
Insider Trading Arrangements [Line Items]
Long-term debt
Long-Term Debt, Excluding Current Maturities
Payment of financing fees
Payments of Financing Costs
Natural gas commodity
Commodity Contract [Member]
Schedule of Short-Term Debt
Schedule of Short-Term Debt [Table Text Block]
Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table
Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member]
Compensation Actually Paid vs. Company Selected Measure
Compensation Actually Paid vs. Company Selected Measure [Text Block]
Equity Awards Adjustments
Equity Awards Adjustments [Member]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Table]
Accounts Receivable, Noncurrent, Credit Quality Indicator [Table]
Derivative instruments
Derivative Liability, Noncurrent
Revenue, over time performance obligation, number
Revenue, Over Time Performance Obligation, Number
Revenue, Over Time Performance Obligation, Number
Regulatory Asset [Domain]
Regulatory Asset [Domain]
Washington Climate Commitment Act compliance
Washington Climate Commitment Act compliance [Member]
Washington Climate Commitment Act compliance
Industry Sector [Domain]
Industry Sector [Domain]
Construction work in progress
Public Utilities, Property, Plant and Equipment, Construction Work in Progress
Plan Name [Axis]
Plan Name [Axis]
Compressed Natural Gas Lease
Compressed Natural Gas Lease [Member]
Compressed Natural Gas Lease
Underlying Asset Class [Domain]
Underlying Asset Class [Domain]
Number of miles
Site Contingency, Number Of Miles
Site Contingency, Number Of Miles
Long Term Incentive Plan
Long Term Incentive Plan [Member]
Long Term Incentive Plan [Member]
Other income (expense), net
Other Nonoperating Income (Expense)
Net amount charged to expense
Defined Benefit Plan Net Amount Charged To Expense
Net periodic benefit cost charged to expense.
Capital expenditures in accrued liabilities
Property, Plant, Equipment Non-Cash
Property, Plant, Equipment Non-Cash
Regulatory liability
Regulatory Liability
Statement of Cash Flows [Abstract]
Statement of Cash Flows [Abstract]
Defined benefit pension plan cash contributions
Payment for Pension and Other Postretirement Benefits
Aggregate Available
Trading Arrangement, Securities Aggregate Available Amount
Income Tax
Income Tax Disclosure [Text Block]
Accounts payable
Accounts Payable, Current
Other
Other Noncash Income (Expense)
Series G Notes
Series G Notes [Member]
Series G Notes
Pay vs Performance Disclosure
Pay vs Performance Disclosure [Table]
Deferred costs and interest
Regulatory Assets, Environmental Regulatory Deferred Cost And Interest
Regulatory Assets, Environmental Regulatory Deferred Cost And Interest
Cash
Business Combination, Consideration Transferred
Retirement Plan Type [Domain]
Retirement Plan Type [Domain]
Entity Filer Category
Entity Filer Category
Other water debt
Other Water Debt [Member]
Other Water Debt
2025 - 2044 Guarantee
2025 - 2044 Guarantee [Member]
2025 - 2044 Guarantee
Schedule of Regulatory Assets
Schedule of Regulatory Assets [Table Text Block]
Accrued asset removal costs
Removal Costs [Member]
Total gain (loss) in pre-tax earnings
Gain (Loss) on Derivative Instruments, Net, Pretax
Remediation recovery percentage
Remediation Recovery Percentage
Remediation Recovery Percentage
Year four
Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four
Conversion ratio, percent of target
Share-Based Compensation Arrangements By Share-Based Payment Award, Conversion Ratio, Percent Of Target
Share-Based Compensation Arrangements By Share-Based Payment Award, Conversion Ratio, Percent Of Target
Stock, Class of Stock [Table]
Stock, Class of Stock [Table]
Current assets:
Assets, Current [Abstract]
Operating revenues
Business Combination, Pro Forma Information, Pro Forma Revenue
Entity Address, Address Line One
Entity Address, Address Line One
Operating leases
Right-of-Use Asset Obtained in Exchange for Operating Lease Liability
Income tax expense (benefit)
Income tax expense (benefit)
Total expense (benefit) for income taxes
Income Tax Expense (Benefit)
Series E Senior Notes
Series E Senior Notes [Member]
Series E Senior Notes
Unrecorded unconditional purchase obligation, purchases
Unrecorded Unconditional Purchase Obligation, Purchases
Less: unamortized debt issuance costs
Unamortized debt issuance costs
Unamortized Debt Issuance Expense
Statement [Table]
Statement [Table]
Regulatory liabilities
Regulatory liability, current
Regulatory Liability, Current
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table]
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table]
Junior Subordinated Debentures
Junior Subordinated Debentures [Member]
Junior Subordinated Debentures
Site contingency, number of other third-party defendants
Site Contingency, Number Of Other Third-Party Defendants
Site Contingency, Number Of Other Third-Party Defendants
Write-offs recognized, net of recoveries
Accounts Receivable, Allowance for Credit Loss, Recovery
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Affiliated Entity [Member]
UNITED STATES