Defined Benefit Plan, Expected Future Benefit Payments in Year Two Defined Benefit Plan, Expected Future Benefit Payment, Year Two Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Commitments and Guarantees [Abstract] Commitments and Guarantees [Abstract] Commitments and Guarantees [Abstract] Payments on long-term debt Repayments of Long-term Debt Repayments of Long-Term Debt Other Nonoperating Income Other Nonoperating Income Cover [Abstract] Cover [Abstract] Lessee, Operating Lease, Liability, Payments, Due after Year Five Lessee, Operating Lease, Liability, to be Paid, after Year Five Equity securities: Equity securities: [Abstract] Equity securities: [Abstract] FERC Authorized Short-term Debt, effective through February 6, 2014 FERC Authorized Short-term Debt, effective through February 6, 2014 FERC Authorized Short-term Debt, effective through February 6, 2014 ClearwaterWind ClearwaterWind [Member] ClearwaterWind Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Wildfire mitigation Wildfire mitigation [Member] Wildfire mitigation Trading Symbol Trading Symbol Unrecorded Unconditional Purchase Obligation, Due within Five Years Unrecorded Unconditional Purchase Obligation, to be Paid, Year Five Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Debt Instrument, Redemption, Period [Axis] Debt Instrument, Redemption, Period [Axis] Generation, excluding thermal: Production, excluding thermal: [Abstract] Production plant, excluding thermal: [Abstract] Non-NEOs Non-NEOs [Member] Common Stock, Dividends, Per Share, Declared Common Stock, Dividends, Per Share, Declared Direct Access customers [Member] Direct Access customers [Member] Direct Access customers [Member] Defined Benefit Plan, Expected Future Benefit Payments in Year Three Defined Benefit Plan, Expected Future Benefit Payment, Year Three Total derivative assets Derivative Assets, Total Fair values as of the balance sheet date of all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments. Balance as of beginning of year Balance as of end of year Accounts Receivable, Allowance for Credit Loss, Current Accounts Receivable, Allowance for Credit Loss, Current Removal Costs [Member] Removal Costs [Member] Line of Credit Facility [Table] Line of Credit Facility [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Inventory, Policy [Policy Text Block] Inventory, Policy [Policy Text Block] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Other Commitment, Due in Second Year Other Commitment, to be Paid, Year Two Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] Fair Value of FInancial Instruments Fair Value Disclosures [Text Block] Award Timing Disclosures [Line Items] Portion at Fair Value Measurement Portion at Fair Value Measurement [Member] Utility, Revenue and Expense Recognition, Policy [Policy Text Block] Utility, Revenue and Expense Recognition, Policy [Policy Text Block] January2024icestormanddamage January2024icestormanddamage [Member] January2024icestormanddamage Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Fair Value - Money market funds Fair Value - Money market funds Fair Value - Money market funds Amounts included in comprehensive income: Amounts included in comprehensive income: [Abstract] Amounts included in comprehensive income: [Abstract] Other current assets: Other current assets: [Abstract] Other current assets: [Abstract] Deferred Tax Assets, Tax Credit Carryforwards Deferred Tax Assets, Tax Credit Carryforwards SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] Plan Name [Domain] Plan Name [Domain] Inventories, at average cost: Energy Related Inventory [Abstract] Weighted Average Number Diluted Shares Outstanding Adjustment Weighted Average Number of Shares Outstanding, Diluted, Adjustment Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment Public Utilities, Property, Plant and Equipment, Other Property, Plant and Equipment Other noncurrent assets Other Assets, Noncurrent Leases [Abstract] Leases [Abstract] First mortgage Bonds - minimum rate First mortgage Bonds - minimum rate First mortgage Bonds - minimum rate Regulatory Assets Regulatory Asset Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Level 3 net unrealized losses that have been fully offset by the effect of regulatory accounting Level 3 realized and unrealized losses offset by the effect of regulatory accounting Level 3 net realized and unrealized losses that have been offset by the effect of regulatory accounting. Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Pension and Other Postretirement Plans Costs [Member] Pension and Other Postretirement Plans Costs [Member] Summary of Significant Accounting Policies [Abstract] Summary of Significant Accounting Policies [Abstract] Summary of Significant Accounting Policies [Abstract] Asset Retirement Obligation, Accretion Expense Asset Retirement Obligation, Accretion Expense Prepaid Expense, Current Prepaid Expense, Current Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest Allowance for Funds Used During Construction, Capitalized Interest Award Timing Method Award Timing Method [Text Block] Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] pension and other postretirement benefits valuation methodology [Policy Text Block] pension and other postretirement benefits valuation methodology [Policy Text Block] Pension and other postretirement benefits valuation methodology [Policy Text Block] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Finance Lease, Weighted Average Remaining Lease Term Finance Lease, Weighted Average Remaining Lease Term Insider Trading Policies and Procedures [Line Items] Adjustment to Compensation, Amount Adjustment to Compensation Amount Compensation Amount Outstanding Recovery Compensation Amount PGE Share of Output PGE Share of Output PGE Share of Output from the individual Public Utility Districts 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] Entity Small Business Entity Small Business Accumulated depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Company Selected Measure Amount Company Selected Measure Amount Tabular List, Table Tabular List [Table Text Block] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Operating Leases, Future Minimum Payments Due, Next Twelve Months Operating Leases, Future Minimum Payments Due, Next 12 Months Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets February2021IceStormAndDamageDeferral February2021IceStormAndDamageDeferral [Member] February2021IceStormAndDamageDeferral Natural gas [Member] Public Utilities, Inventory, Fuel [Member] Earning a return [Member] Earning a return [Member] Earning a return [Member] Schedule of allocation of plan assets [Table] schedule of allocation of plan assets [Table] schedule of allocation of plan assets [Table] Finance Lease, Liability, Undiscounted Excess Amount Finance Lease, Liability, Undiscounted Excess Amount Schedule of Price Risk Derivatives [Table Text Block] Schedule of Price Risk Derivatives [Table Text Block] Credit Facility [Domain] Credit Facility [Domain] Noncurrent Liabilities, Commodity Contracts: [Abstract] Noncurrent Liabilities, Commodity Contracts: [Abstract] Noncurrent Liabilities, Commodity Contracts: [Abstract] Taxes other than income taxes Taxes, Miscellaneous Accounts and Financing Receivables [Table] Accounts and Financing Receivables [Table] Private equity funds Private Equity Funds, US [Member] Non Qualified Benefit Plans [Member] Non Qualified Benefit Plans [Member] Non Qualified Benefit Plans [Member] PowerCostAdjustmentMechanismDeferral PowerCostAdjustmentMechanismDeferral [Member] PowerCostAdjustmentMechanismDeferral Proceeds from Income Tax Refunds Proceeds from Income Tax Refunds Employee Stock Option Share-Based Payment Arrangement, Option [Member] Other Proceeds from (Payments for) Other Financing Activities Unrecorded Unconditional Purchase Obligation, Imputed Interest Unrecorded Unconditional Purchase Obligation, Imputed Interest Interest Income, Interest-Earning Asset Interest Income, Interest-Earning Asset Pension Plan [Member] Pension Plans, Defined Benefit [Member] Pension Plan [Member] Finance Lease, Weighted Average Discount Rate, Percent Finance Lease, Weighted Average Discount Rate, Percent Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Finance Lease, Liability, Payments, Due Year One Finance Lease, Liability, to be Paid, Year One Award Type [Axis] Award Type [Axis] Company contribution percentage to 401k for post 2008 hires Company contribution percentage to 401k for post 2008 hires Company contribution percentage of participating employee's base salary for employees hired post January 31, 2009, regardless of whether the employee contributes to the 401k plan. Alternative revenue programs, net of amortization Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Estimate of Transaction Price Contract with Customer, Liability, Cumulative Catch-up Adjustment to Revenue, Change in Estimate of Transaction Price Total deferred income tax liabilities Deferred Tax Liabilities, Net Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Public Utility Property, Plant, and Equipment [Table Text Block] Public Utility Property, Plant, and Equipment [Table Text Block] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Total liabilities Liabilities upper range of costs upper range of costs upper range of costs Fair Value, Option, Quantitative Disclosures [Line Items] Fair Value, Option, Quantitative Disclosures [Line Items] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Expiration Date Trading Arrangement Expiration Date Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Insurance contracts, at cash surrender value Cash Surrender Value, Fair Value Disclosure Operating Lease, Liability, Current Operating Lease, Liability, Current Total Shareholder Return Amount Total Shareholder Return Amount Finance Lease, Liability, Payments, Due in Rolling Year Two Finance Lease, Liability, to be Paid, Rolling Year Two Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Asset Retirement Obligation, Liabilities Incurred Asset Retirement Obligation, Liabilities Incurred Debt Instrument [Line Items] Debt Instrument [Line Items] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Current Assets, Commodity Contracts: Current Assets, Commodity Contracts: [Abstract] Commodity contracts: [Abstract] Diluted Weighted Average Number of Shares Outstanding, Diluted Weighted Average Number of Shares Outstanding, Diluted Regulatory Depreciation and Amortization, Policy [Policy Text Block] Regulatory Depreciation and Amortization, Policy [Policy Text Block] Unrealized Gain Loss On Derivatives [Member] Unrealized Gain Loss On Derivatives [Member] Unrealized Gain Loss On Derivatives [Member] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Performance based stock award percentage - maximum Performance based stock award percentage - maximum Performance based stock award percentage - maximum Unrecorded Unconditional Purchase Obligation, Due within Four Years Unrecorded Unconditional Purchase Obligation, to be Paid, Year Four Current Liabilities, Commodity Contracts: [Abstract] Current Liabilities, Commodity Contracts: [Abstract] Current Liabilities, Commodity Contracts: [Abstract] Other Regulatory Assets Earning a Return [Member] Other Regulatory Assets Earning a Return [Member] Other Regulatory Assets Earning a Return [Member] Litigation Case [Axis] Litigation Case [Axis] Purchased power and fuel Utilities Operating Expense, Purchased Power In service, net In service, net Public Utilities, Property, Plant and Equipment, Plant in Service, Net Public Utilities, Property, Plant and Equipment, Plant in Service, Net LettersOfCreditOutstandingAmountForPriceRiskManagement LettersOfCreditOutstandingAmountForPriceRiskManagement LettersOfCreditOutstandingAmountForPriceRiskManagement Investment Income, Net Investment Income, Net Other Commitment, Due in Fourth Year Other Commitment, to be Paid, Year Four Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Long-term Purchase Commitment by Category of Item Purchased [Axis] Category of Item Purchased [Axis] Category of Item Purchased [Axis] Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of Change in Asset Retirement Obligation [Table Text Block] Utility Plant [Domain] Utility Plant [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Authorized Deferred Derivative Gain (Loss) [Member] Deferred Derivative Gain (Loss) [Member] Document Fiscal Period Focus Document Fiscal Period Focus 2026 Long-Term Debt, Maturity, Year Four All Executive Categories All Executive Categories [Member] Company contribution percent to 401k for bargaining employees Company contribution percent to 401k for bargaining employees For bargaining employees, who are subject to the International Brotherhood of Electrical Workers Local 125 agreements, the Company contributes a stated amount per compensable hour plus this percentage of the employee’s base salary, whether or not the employee contributes to the 401k Plan. Statement of Financial Position Location, Balance [Domain] Statement of Financial Position Location, Balance [Domain] Collective trust funds Equity Securities [Member] Future Amortization Expense, Year Two Finite-Lived Intangible Asset, Expected Amortization, Year Two Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] ASSETS Assets [Abstract] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Document Type Document Type Defined Benefit Plan, Equity Securities, US Defined Benefit Plan, Equity Securities, US [Member] Balance Sheet Location [Domain] Derivative, Name [Domain] Derivative Contract [Domain] Schedule of Regulatory Assets and Liabilities [Text Block] Schedule of Regulatory Assets and Liabilities [Text Block] Actuarial loss (gain) Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Proceeds from (Repayments of) Commercial Paper Proceeds from (Repayments of) Commercial Paper Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Asset Retirement Obligations, Significant Changes Asset Retirement Obligations, Significant Changes Other income: Other Income and Expenses [Abstract] Defined Benefit Plan [Table] Defined Benefit Plan [Table] Collateral Aggregate Fair Value Collateral Aggregate Fair Value The aggregate fair value of assets that would be required to be posted as collateral for derviative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period. Transmission Public Utilities, Property, Plant and Equipment, Transmission, Useful Life Tax Credit Carryforward, Federal Tax Credit Carryforward, Federal The amount of the federal tax credit carryforward, berfore tax effects, available to reduce future taxable income under enacted tax laws. Regulatory Assets [Line Items] Regulatory Asset [Line Items] Maximum [Member] Maximum [Member] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Regulated Operating Revenue, Electric, Non-Nuclear Regulated Operating Revenue, Electric, Non-Nuclear Noncurrent assets: Assets, Noncurrent [Abstract] Statistical Measurement [Axis] Statistical Measurement [Axis] Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest, Total Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Depreciation and amortization Deferred Tax Liabilities, Property, Plant and Equipment Name Outstanding Recovery, Individual Name Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Variable Lease, Cost Variable Lease, Cost Money market funds Money Market Funds, at Carrying Value (Decrease) increase in cash and cash equivalents Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Period Increase (Decrease), Excluding Exchange Rate Effect Award Timing Predetermined Award Timing Predetermined [Flag] Electricity Volume Related to Derivative Instruments Held at Balance Sheet Date, Commodity Contracts, Electricity Net volume related to the reporting entity's derivative instruments as of the balance sheet date having arisen from price risk management activities. Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Long-term Debt Long-Term Debt [Text Block] Diluted Earnings Per Share, Diluted Benefit obligation: Defined Benefit Plan, Expected Future Benefit Payment [Abstract] Revenue from Contract with Customer [Policy Text Block] Revenue from Contract with Customer [Policy Text Block] Current Income Tax Expense (Benefit) Current Income Tax Expense (Benefit) Regulatory Liability [Domain] Regulatory Liability [Domain] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Colstrip - Transmission Colstrip - Transmission [Member] Colstrip - Transmission Retirement Benefits [Abstract] Retirement Benefits [Abstract] Deferred income tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Preferred Stock, Shares Issued Preferred Stock, Shares Issued RemainingAmountsOfRegulatoryLiabilitesForWhichNoInterstAccruesDuringRecoveryPeriodIsProvided RemainingAmountsOfRegulatoryLiabilitesForWhichNoInterstAccruesDuringRecoveryPeriodIsProvided RemainingAmountsOfRegulatoryLiabilitesForWhichNoInterstAccruesDuringRecoveryPeriodIsProvided Electric Transmission [Member] Electric Transmission [Member] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Decrease (increase) in receivables and unbilled revenues Increase (Decrease) in Receivables Derivative, Collateral, Obligation to Return Securities Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Security Not Offset Deferred Tax Liabilities, Other Deferred Tax Liabilities, Other Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Finance Lease, Liability, Payments, Due in Next Rolling 12 Months Finance Lease, Liability, to be Paid, Next Rolling 12 Months Electricity Commodity Contract Liabilities, Electricity Carrying amount as of the balance sheet date of the liabilities arising from commodity contracts related to purchases or sales of electricity. Net income Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components Defined Benefit Plan, Effect of One-Percentage-Point Increase on Service and Interest Cost Components Income tax expense Income tax expense Income Tax Expense (Benefit) Interest cost on benefit obligation Defined Benefit Plan, Interest Cost Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Allocation of Financial Asset to Hierarchy Levels [Policy Text Block] Allocation of Financial Asset to Hierarchy Levels [Policy Text Block] Allocation of Financial Asset to Hierarchy Levels [Policy Text Block] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Liabilities from price risk management activities: [Abstract] Liabilities from price risk management activities: [Abstract] Liabilities from price risk management activities: [Abstract] Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Interest expense, net Interest Expense, Operating and Nonoperating 2020LaborDayWildfireDeferral 2020LaborDayWildfireDeferral [Member] 2020LaborDayWildfireDeferral Company match post 2008 hire Company match post 2008 hire Company match, percentage of participating employee's base salary for employees hired post January 31, 2009. Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life Public Utilities, Property, Plant and Equipment, Other Property Plant and Equipment, Useful Life Other Operating Activities, Cash Flow Statement Other Operating Activities, Cash Flow Statement All Adjustments to Compensation All Adjustments to Compensation [Member] Accrued employee compensation and benefits Employee-related Liabilities, Current Net liabilities from price risk management activities as of end of year Net Liabilities From Price Risk Management Activities Classified As Level 3 Net Liabilities From Price Risk Management Activities Classified as Level 3 Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Regulatory Asset [Axis] Regulatory Asset [Axis] Electric utility plant: Public Utilities, Property, Plant and Equipment, Net [Abstract] Credit Risk Contract [Member] Credit Risk Contract [Member] Franchise Tax [Policy Text Block] franchise tax [Policy Text Block] franchise tax [Policy Text Block] Scenario [Domain] Scenario [Domain] Nuclear decommissioning trust Decommissioning Fund Investments, Fair Value Name of Property [Domain] Name of Property [Domain] US Government Agencies Debt Securities US Government Agencies Debt Securities [Member] Pelton/Round Butte Member Pelton/Round Butte Member [Member] Pelton/Round Butte Member Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Entity Address, State or Province Entity Address, State or Province Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Electricity Commodity Contract Liability, Noncurrent, Electricity Carrying amount as of the balance sheet date of the liability arising from commodity contracts related to electricity which are expected to be settled after a year or beyond the normal operating cycle, if longer. Hydro estimated average service life - hydro production plant estimated average service life - hydro production plant Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Portion at Other than Fair Value Measurement Portion at Other than Fair Value Measurement [Member] Fair Value, Option, Eligible Item or Group [Domain] Financial Instruments [Domain] Accounts, Notes, Loans and Financing Receivable [Line Items] Accounts, Notes, Loans and Financing Receivable [Line Items] Income Taxes Note [Abstract] Income Taxes Note [Abstract] Income Taxes Note [Abstract] Vesting [Domain] Vesting [Domain] Outstanding, Weighted Average Grant Date Fair Value Outstanding, Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Liabilities and Equity [Abstract] Liabilities and Equity [Abstract] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Asset Retirement Obligation, Cash Paid to Settle Asset Retirement Obligation, Cash Paid to Settle Asset Retirement Obligation, Cash Paid to Settle Preferred Stock, No Par Value Preferred Stock, No Par Value Restatement Determination Date Restatement Determination Date Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Property, Plant and Equipment [Table] Schedule of Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Operating Lease, Right-of-Use Asset Operating Lease, Right-of-Use Asset Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Commercial Paper, Maximum Term Commercial Paper, Maximum Term Commercial Paper, Maximum Term Jointly-owned Plant [Text Block] Jointly-owned Plant [Text Block] Jointly-owned Plant [Text Block] Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Other Commitment, Due in Next Twelve Months Other Commitment, to be Paid, Year One Dividends payable Dividends Payable, Current Non-qualified benefit [Policy Text Block] Non-qualified benefit [Policy Text Block] Non-qualified benefit plans [Policy Text Block] Earnings Per Share Earnings Per Share [Text Block] Other Regulatory Assets (Liabilities) [Member] Other Regulatory Assets (Liabilities) [Member] Operating expenses: Costs and Expenses [Abstract] Granted, Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Natural gas Commodity Contract Liabilities, Natural gas Carrying amount as of the balance sheet date of the liabilities arising from commodity contracts related to purchases or sales of natural gas. Income Tax, Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Regulated Operation, Jointly Owned Utility Plant [Table] Regulated Operation, Jointly Owned Utility Plant [Table] Schedule of Future Minimum Lease Payments for Capital Leases [Table Text Block] Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Non-qualified benefit plan liabilities Liability, Other Postretirement Defined Benefit Plan, Noncurrent PEO PEO [Member] Asset Retirement Obligations Asset Retirement Obligation Disclosure [Text Block] Name Trading Arrangement, Individual Name Defined Benefit Plan, Funded (Unfunded) Status of Plan Defined Benefit Plan, Funded (Unfunded) Status of Plan Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Property, Plant and Equipment, Type [Axis] Property, Plant and Equipment by Type [Axis] Long-Lived Tangible Asset [Axis] Residential [Member] Residential [Member] Residential [Member] Entity Public Float Entity Public Float As of January 1 Defined Benefit Plan, Benefit Obligation Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Share-based Liabilities Paid Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Share-Based Liabilities Paid Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Accrued dividends payable Dividends Payable 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] Jointly Owned Utility Plant Interests [Line Items] Jointly Owned Utility Plant Interests [Line Items] Cash and Cash Equivalents, Fair Value Disclosure Cash and Cash Equivalents, Fair Value Disclosure Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Local Phone Number Local Phone Number Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Valuation Allowance Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Operating Expenses Operating Expenses Change in Accounting Estimate by Type [Axis] Change in Accounting Estimate by Type [Axis] Derivative, Net Liability Position, Aggregate Fair Value Derivative, Net Liability Position, Aggregate Fair Value Changes in working capital: Increase (Decrease) in Operating Capital [Abstract] Liabilities, Noncurrent [Abstract] Liabilities, Noncurrent [Abstract] PEO Total Compensation Amount PEO Total Compensation Amount Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Accrued interest payable Interest Payable, Current Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Recorded Third-Party Environmental Recoveries, Amount Recorded Third-Party Environmental Recoveries, Amount Fuel Energy Related Inventory Debt Disclosure [Abstract] Total Amounts included in comprehensive income Total Amounts included in comprehensive income Total Amounts included in comprehensive income during the period from Defined Benefit Plans. Commodity [Axis] Commodity [Axis] Commodity [Axis] Common Stock Shares Common Stock [Member] Line of Credit Facility [Abstract] Line of Credit Facility [Abstract] Leveraged Leases, Balance Sheet, Investment in Leveraged Leases, Net Leveraged Leases, Balance Sheet, Investment in Leveraged Leases, Net Right to reclaim cash collateral Derivative Liability, Subject to Master Netting Arrangement, Collateral, Right to Reclaim Cash Not Offset Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Segment Reporting [Abstract] Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Entity Central Index Key Entity Central Index Key Stock-based compensation Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture Loss Contingency, Damages Sought, Value Loss Contingency, Damages Sought, Value Margin Deposit Assets Margin Deposit Assets Statement, Scenario [Axis] Scenario [Axis] Plant Retirement and Abandonment, Policy [Policy Text Block] Plant Retirement and Abandonment, Policy [Policy Text Block] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Debt Instrument, Covenant Description Debt Instrument, Covenant Ratio Debt Instrument, Covenant Ratio Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Eligible Item or Group for Fair Value Option [Axis] Financial Instrument [Axis] Stock-based Compensation, Forfeiture Rate Stock-based Compensation, Forfeiture Rate Forfeiture rate used in determining the period stock-based compensation expense. Segment Reporting Disclosure Segment Reporting Disclosure [Text Block] Current portion of long-term debt Less: current portion of long-term debt Long-term Debt, Current Maturities Long-Term Debt, Current Maturities Asset Retirement Obligation [Abstract] Asset Retirement Obligation [Abstract] Unrecorded Unconditional Purchase Obligation, Due within One Year Unrecorded Unconditional Purchase Obligation, to be Paid, Year One Other Loans Payable, Long-Term, Noncurrent Other Loans Payable, Long-Term, Noncurrent Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Measurement Basis [Axis] Measurement Basis [Axis] Gain (Loss) on Contract Termination Gain (Loss) on Contract Termination Title Trading Arrangement, Individual Title letter of credit facility letter of credit facility letter of credit facility Number of Union Employees Subject to Agreement B Number of Union Employees Subject to Agreement B Number of employees subject to collective bargaining agreement B. City Area Code City Area Code Current liabilities: Liabilities, Current [Abstract] Auditor Location Auditor Location Total current derivative liabilities Current Derivative Liabilities Fair values as of the balance sheet date for all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be settled within one year of the normal operating cycle, if longer. Public Utilities, Property, Plant and Equipment, Net Public Utilities, Property, Plant and Equipment, Net Public Utilities, Property, Plant and Equipment, Net Fair Value Option, Disclosures [Table Text Block] Fair Value Option, Disclosures [Table Text Block] Revenue [Policy Text Block] Revenue [Policy Text Block] COVID-19Deferral COVID-19Deferral [Member] COVID-19Deferral Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Credit Derivatives Contract Type [Domain] Credit Derivatives Contract Type [Domain] Common Stock Amount Common Stock Including Additional Paid in Capital [Member] Schedule of Jointly Owned Utility Plants [Table Text Block] Schedule of Jointly Owned Utility Plants [Table Text Block] 2038 Member 2038 Member [Member] 2038 Member Electricity Commodity Contract Asset, Electricity Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to purchases or sales of electricity. Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Employee Benefits [Abstract] Employee Benefits [Abstract] Employee Benefits [Abstract] Payments for Repurchase of Common Stock Payments for Repurchase of Common Stock Long-term debt, net of current portion Long-Term Debt, Excluding Current Maturities 2053 Member 2053 Member [Member] 2053 Member Utility plant Asset Retirement Obligation - Utility Plant Asset Retirement Obligation - Utility Plant 2030 Member [Member] 2030 Member [Member] 2030 Member Decommissioning Liability, Noncurrent Decommissioning Liability, Noncurrent Share-based Payment Arrangement, Expensed and Capitalized, Amount [Abstract] Share-Based Payment Arrangement, Recognized Amount [Abstract] Earnings per share: Earnings Per Share [Abstract] Equity: Equity [Abstract] Retained earnings Retained Earnings (Accumulated Deficit) Power Cost Deadband - Lower Threshold Power Cost Deadband - Lower Threshold Lower threshold of the net variable power cost deadband as established under the Company's annual update tariff. Class of Stock [Domain] Class of Stock [Domain] Quantifying Misstatement in Current Year Financial Statements, Amount Public Utilities, Property, Plant and Equipment, Distribution Public Utilities, Property, Plant and Equipment, Distribution Asset Retirement Obligation Costs [Member] Asset Retirement Obligation Costs [Member] Administrative and other General and Administrative Expense 2024 Long-Term Debt, Maturity, Year Two Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Schedule of Short-term Debt [Table Text Block] Schedule of Short-Term Debt [Table Text Block] Equity Awards Adjustments Equity Awards Adjustments [Member] Stock Purchase Plan [Text Block] Stock Purchase Plan [Text Block] Stock Purchase Plan Text Block Operating Lease, Liability Operating Lease, Liability Operating Lease, Liability Non-utility property Asset Retirement Obligation - Non-utility property Asset Retirement Obligation - Non-utility property Underlying Securities Award Underlying Securities Amount Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Commodity contracts: [Abstract] Commodity contracts: [Abstract] Commodity contracts: [Abstract] Leveraged Leases, Balance Sheet, Investment in Leveraged Leases Leveraged Leases, Balance Sheet, Investment in Leveraged Leases Regulatory assets--current Regulatory Asset, Current Finance Lease, Liability, Payments, Due Year Five Finance Lease, Liability, to be Paid, Year Five Increase (Decrease) in Other Regulatory Assets Increase (Decrease) in Other Regulatory Assets Amendment Flag Amendment Flag Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Commodity Contract Asset, Noncurrent, Electricity Commodity Contract Asset, Noncurrent, Electricity Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to electricity which are expected to be settled after a year or beyond the normal operating cycle, if longer. Finance Lease, Right-of-Use Asset, Amortization Finance Lease, Right-of-Use Asset, Amortization Pollution Control Revenue Bonds at 2,125% Pollution Control Revenue Bonds at 2.125% Pollution Control Revenue Bonds at 2.125% Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Proceeds from Short-term Debt Proceeds from Short-Term Debt Liabilities from price risk management activities--noncurrent Derivative Liability, Noncurrent Entity Address, Postal Zip Code Entity Address, Postal Zip Code Distribution Public Utilities, Property, Plant and Equipment, Distribution, Useful Life Long-term Purchase Commitment [Table] Long-Term Purchase Commitment [Table] Other Postretirement Benefits Cost (Reversal of Cost) Other Postretirement Benefits Cost (Reversal of Cost) Other, net Payments for (Proceeds from) Other Investing Activities 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] Auditor Name Auditor Name Forfeited, Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Employee Stock Purchase Plan, Purchased Stock Value Limitation Employee Stock Purchase Plan, Purchased Stock Value Limitation Employee Stock Purchase Plan, Purchased Stock Value Limitation Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Pollution Control Revenue Bonds at 2.375% Pollution Control Revenue Bonds at 2.375% Pollution Control Revenue Bonds at 2.375% 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] Natural gas financial swaps Natural gas financial swaps Natural gas financial swaps Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization, Percent Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amortization, Percent Sales of nuclear decommissioning trust securities Proceeds from Sale, Maturity and Collection of Investments Fair Value of Financial Instruments [Abstract] Fair Value of Financial Instruments [Abstract] Fair Value of Financial Instruments [Abstract] Portion at Fair Value Measurement Fair Value Measurement [Domain] (Decrease) increase in payables and accrued liabilities Increase (Decrease) in Accounts Payable Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Finance Lease, Principal Payments Finance Lease, Principal Payments Pollution Control Revenue Bonds, rates at 2.13% and 2.38%, due 2033 Long-Term Pollution Control Bond Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [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] Weighted-average shares outstanding (in thousands): Weighted Average Number of Shares Outstanding, Diluted [Abstract] Total assets Assets Assets Capital expenditures Payments to Acquire Property, Plant, and Equipment Other noncurrent liabilities Other Liabilities, Noncurrent Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Commitments and Contingencies (see notes) Commitments and Contingencies Share-based Payment Arrangement [Policy Text Block] Share-Based Payment Arrangement [Policy Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Termination Date Trading Arrangement Termination Date Commitments and Guarantees [Text Block] Commitments and Guarantees [Text Block] Commitments and Guarantees Text Block Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Lessee, Operating Lease, Liability, Payments, Due Year Two Lessee, Operating Lease, Liability, to be Paid, Year Two Other Postretirement Benefit Plans assets: [Abstract] Other Postretirement Benefit Plans assets: [Abstract] Other Postretirement Benefit Plans assets: [Abstract] Price Risk Management [Abstract] Price Risk Management [Abstract] Price Risk Management [Abstract] 2023 Long-Term Debt, Maturity, Year One Derivative Asset, Fair Value, Amount Offset Against Collateral Derivative Asset, Including Not Subject to Master Netting Arrangement, after Offset and Deduction Debt Instrument [Axis] Debt Instrument [Axis] Colstrip [Member] Colstrip [Member] Colstrip [Member] Defined Benefit Pension Plan assets: Defined Benefit Plan, Funded (Unfunded) Status of Plan [Abstract] Derivative, Collateral, Obligation to Return Cash Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash Not Offset Revenue Recognition [Abstract] Revenue Recognition [Abstract] Net Income (Loss) Net Income (Loss) Attributable to Parent Asset Retirement Obligation, Period Increase (Decrease) Asset Retirement Obligation, Period Increase (Decrease) Trading Arrangement: Trading Arrangement [Axis] Revenues, net Revenue from Contract with Customer, Including Assessed Tax Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Balance Sheet Components [Abstract] Balance Sheet Components [Abstract] Balance Sheet Components [Abstract] Line of Credit Facility, Current Borrowing Capacity Line of Credit Facility, Current Borrowing Capacity Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Assets [Member] Available-for-Sale Securities [Member] Balance Sheet Components Details of Certain Balance Sheet Accounts Disclosure [Text Block] Details of Certain Balance Sheet Accounts Entity File Number Entity File Number Employee Benefits Assumptions [Table] Defined Benefit Plan, Assumptions [Table Text Block] Dividend Reinvestment and Direct Stock Purchase Plan, Number of Available Shares Dividend Reinvestment and Direct Stock Purchase Plan, Number of Available Shares Dividend Reinvestment and Direct Stock Purchase Plan, Number of Available Shares Entity Address, Address Line One Entity Address, Address Line One Federal Current Federal Tax Expense (Benefit) Dividends declared Dividends, Common Stock Name Forgone Recovery, Individual Name Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term Award Date [Domain] Award Date [Domain] BenjaminFelton [Member] BenjaminFelton Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Other non-cash income and expenses, net Other Noncash Income (Expense) Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Power Cost Deadband - Upper Threshold Power Cost Deadband - Upper Threshold Upper threshold of the net variable power cost deadband established under the Company's annual update tariff. Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Public Utility [Axis] Public Utility [Axis] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Non Qualified Benefit Plans [Member] Other Pension, Postretirement and Supplemental Plans [Member] Other Pension, Postretirement and Supplemental Plans [Member] employee stock purchase plan shares authorized employee stock purchase plan shares authorized employee stock purchase plan shares authorized Adjustment to Compensation: Adjustment to Compensation [Axis] Regulatory Agency [Axis] Regulatory Agency [Axis] Reliabilitycontingencyevent Reliabilitycontingencyevent [Member] Reliabilitycontingencyevent Litigation Case [Domain] Litigation Case [Domain] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Natural Gas Realized and Unrealized Gains and Losses, Net, Commodity Contracts, Natural Gas Realized and unrealized gains and losses, net on commodity contracts related to natural gas not designated as hedging instruments included in purchased power and fuel expense in the statement of income. Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Public Utilities, Property, Plant and Equipment, Intangible Public Utilities, Property, Plant and Equipment, Intangible Public Utilities, Property, Plant and Equipment, Intangible Basic Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Basic Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] (Increase) in margin deposits Increase (Decrease) in Margin Deposits Outstanding Natural gas Volume Related to Derivative Instruments at Balance Sheet Date, Commodity Contracts, Natural Gas Net volume associated with the reporting entity's derivative instruments recorded as of the balance sheet date having arisen from price risk management activities related to natural gas. Total shareholders' equity Balance Balance Equity, Including Portion Attributable to Noncontrolling Interest Regulatory Agency [Domain] Regulatory Agency [Domain] Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Other Commitment, Due in Third Year Other Commitment, to be Paid, Year Three Name Awards Close in Time to MNPI Disclosures, Individual Name Loss Contingency, Range of Possible Loss, Portion Not Accrued Loss Contingency, Range of Possible Loss, Portion Not Accrued Trojan decommissioning [Member] Trojan decommissioning [Member] Trojan decommissioning [Member] Represents the portion of the associated concept that is related to the decommissioning of the former Trojan nuclear power plant. Entity Filer Category Entity Filer Category Balance, shares Balance, shares Shares, Issued Collateral Already Posted, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value Finance Lease, Liability, Payments, Due in Rolling after Year Five Finance Lease, Liability, to be Paid, after Rolling Year Five Loss Contingencies [Line Items] Loss Contingencies [Line Items] 2033 Member 2033 Member [Member] 2033 Member Flow through depreciation and cost basis differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation, Percent Derivative Asset, Noncurrent Derivative Asset, Noncurrent Asset Retirement Obligation, Liabilities Settled Asset Retirement Obligation, Liabilities Settled Public Utilities, Policy [Policy Text Block] Public Utilities, Policy [Policy Text Block] Defined Benefit Pension Plan [Member] Defined Benefit Pension Plan [Member] Other Pension Plan [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block] Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block] Lease, Cost [Table Text Block] Lease, Cost [Table Text Block] Debt Securities [Member] Debt Securities [Member] Fnancial swaps - electricity Fnancial swaps - electricity Fnancial swaps - electricity Accrued expenses and other current liabilities Other Liabilities, Current Other Liabilities, Current Asset Retirement Obligation, Revision of Estimate Asset Retirement Obligation, Revision of Estimate All Trading Arrangements All Trading Arrangements [Member] Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Derivatives, Fair Value [Line Items] Derivative [Line Items] Derivative [Line Items] Pay vs Performance Disclosure [Line Items] Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress Net gain or loss recognized in the statement of income offset by regulatory accounting Net gain or loss recognized in the statement of income offset by regulatory accounting Net gain or loss recognized in the statement of income for derivative instruments related to price risk management activities offset by regulatory accounting. Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Derivative [Table] Derivative [Table] Long-term Debt, Unclassified [Abstract] Long-Term Debt, Unclassified [Abstract] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Derivative Liability, Fair Value, Amount Not Offset Against Collateral Derivative Liability, Subject to Master Netting Arrangement, before Offset of Collateral Increase (Decrease) in Regulatory Liabilities Increase (Decrease) in Regulatory Liabilities Other working capital items, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Performance based stock award percentage - minimum Performance based stock award percentage - minimum Performance based stock award percentage - minimum Other Performance Measure, Amount Other Performance Measure, Amount Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Future Amortization Expense, Year Three Finite-Lived Intangible Asset, Expected Amortization, Year Three Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service Lessee, Operating Leases Lessee, Operating Leases [Text Block] Common Stock, Shares, Outstanding Common Stock, Shares, Outstanding Industrial [Member] Industrial [Member] Industrial [Member] Operating Lease, Cost Operating Lease, Cost Weighted daily average interest rate Short-Term Debt, Weighted Average Interest Rate, at Point in Time M.AngelicaEspinosa [Member] M.AngelicaEspinosa Operating Lease, Liability, Noncurrent Operating Lease, Liability, Noncurrent Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Benefit payments Defined Benefit Plan, Benefits Paid (Deprecated 2017-01-31) Defined Benefit Plan, Benefit Obligation, Benefits Paid Finance Lease, Interest Expense Finance Lease, Interest Expense Regulated Operation, Regulatory Asset [Table] Regulated Operation, Regulatory Asset [Table] Total noncurrent derivative liabilities Noncurrent Derivative Liabilities Fair values as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be settled after one year or normal operating cycle, if longer. Schedule of Regulatory Liabilities [Table Text Block] Schedule of Regulatory Liabilities [Table Text Block] Service cost Defined Benefit Plan, Service Cost Jointly-owned Plant [Abstract] Jointly-owned Plant [Abstract] Jointly-owned Plant [Abstract] Proceeds from Issuance or Sale of Equity Proceeds from Issuance or Sale of Equity Entity Tax Identification Number Entity Tax Identification Number Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-Term Debt Instruments [Table Text Block] OtherPostretirementDefinedBenefitPlanLiabilityCurrent OtherPostretirementDefinedBenefitPlanLiabilityCurrent This represents the current liability recognized in the balance sheet that is associated with other postretirement defined benefit plans (excluding pension plans). First Mortgage Bonds, rates range from 1.82% to 6.88%, with a weighted average rate of 4.09% in 2022 and 4.11% in 2021, due at various dates through 2051 Secured Debt Retirement Plan Type [Axis] Retirement Plan Type [Axis] Money Market Funds Money Market Funds [Member] Accrued expenses and other current liabilities: Accrued expenses and other current liabilities: [Abstract] Accrued expenses and other current liabilities: [Abstract] Taxes Payable, Current Taxes Payable, Current Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Instruments [Table Text Block] Deferred income tax assets: Deferred Tax Assets, Net [Abstract] Asset retirement obligations Asset Retirement Obligations, Noncurrent Asset Retirement Obligations, Noncurrent Plan Name [Axis] Plan Name [Axis] Finance Lease, Liability, Payments, Due after Year Five Finance Lease, Liability, to be Paid, after Year Five Statement, Equity Components [Axis] Equity Components [Axis] Equity Components [Axis] Finance Lease, Liability, Payment, Due Finance Lease, Liability, to be Paid Unrecorded Unconditional Purchase Obligation, Due within Two Years Unrecorded Unconditional Purchase Obligation, to be Paid, Year Two Boardman refund [Domain] Boardman refund [Domain] Boardman refund [Domain] Other current assets Other Assets, Current Other Assets, Current Accounts Receivable [Policy Text Block] Accounts Receivable [Policy Text Block] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Electricity Commodity Contract Asset, Current, Electricity Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to electricity which are expected to be settled within a year or normal operating cycle, if longer. Trust [Domain] Trust [Domain] Trust [Domain] Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Net of Forfeitures [Abstract] Share-based Payment Arrangement, Amount Capitalized Share-Based Payment Arrangement, Amount Capitalized Total operating expenses Costs and Expenses Costs and Expenses Natural Gas Commodity Contract Liability, Noncurrent, Natural Gas Carrying amount as of the balance sheet date of the liability arising from commodity contracts related to natural gas which are expected to be settled after a year or beyond the normal operating cycle, if longer. Net realized losses net realized losses net realized losses on price risk management Payment for Pension Benefits Payment for Pension Benefits Unrecorded Unconditional Purchase Obligation, Due within Three Years Unrecorded Unconditional Purchase Obligation, to be Paid, Year Three Non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Lessee, Operating Lease, Liability, Payments, Due Year Five Lessee, Operating Lease, Liability, to be Paid, Year Five Power Cost [Policy Text Block] power cost [Policy Text Block] power cost, including the application of the power cost adjustment mechanism (PCAM) [Policy Text Block] Award Date [Axis] Award Date [Axis] Amounts included in AOCL: Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax [Abstract] Weighted Average [Member] Weighted Average [Member] Stock Repurchased During Period, Value Stock Repurchased During Period, Value 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] Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Environmental Remediation Site [Domain] Environmental Remediation Site [Domain] Cash and cash equivalents Cash and cash equivalents, beginning of year Cash and cash equivalents, end of year Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Deferred Income Tax Charge [Member] Deferred Income Tax Charge [Member] Revenue Subject to Refund [Member] Revenue Subject to Refund [Member] Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Current assets: Assets, Current [Abstract] Priest Rapids and Wanapum [Member] Priest Rapids and Wanapum [Member] Priest Rapids and Wanapum [Member] Minimum Guarantees, Policy [Policy Text Block] Minimum Guarantees, Policy [Policy Text Block] Stock-based Compensation, Attainment of Performance Goals That Allows Vesting Stock-based Compensation, Attainment of Performance Goals That Allows Vesting Rate used in the determination of stock-based compensation expense for performance stock units. Assumed level of attainment of performance goals that allows the vesting of this percent. Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Natural Gas [Member] Natural Gas [Member] Natural Gas Commodity Contract Liability, Current, Natural Gas Carrying amount as of the balance sheet date of the liability arising from the commodity contracts related to natural gas which are expected to be settled within a year or normal operating cycle, if longer. Corporate debt securities held in decommissioning trust assets Corporate debt securities held in decommissioning trust assets Corporate debt securities held in decommissioning trust assets Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Deferred investment tax credits Deferred investment tax credits Deferred investment tax credits Product and Service [Domain] Product and Service [Domain] Regulatory Assets Earning a Rate of Return at the Approved Rate Regulatory Assets Earning a Rate of Return at the Approved Rate Regulatory assets earning a rate of return at the approved rate. Liabilities [Member] Derivative Financial Instruments, Liabilities [Member] Vested, Weighted Average Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Remaining Amounts of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Preferred Stock, Shares Outstanding Preferred Stock, Shares Outstanding Security Exchange Name Security Exchange Name Total commodity contracts Total commodity contracts Total commodity contracts Company match pre 2009 hire Company match pre 2009 hire Company match, percentage of participating employee's base salary for employees hired pre February 1, 2009. Employee Stock Purchase Plan, Purchase Price Employee Stock Purchase Plan Purchase Price Employee Stock Purchase Plan, Purchase Price reflected in percentage of FMV at Purchase date. State and local Current State and Local Tax Expense (Benefit) Site Contingency, Names of Other Potentially Responsible Parties Number Of Names Of Other Potentially Responsible Parties Number Of Names Of Other Potentially Responsible Parties Short-term Debt Short-Term Debt Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Total Other Commitment Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Wells [Member] Wells [Member] Wells [Member] Common Stock, Shares, Issued Common Stock, Shares, Issued Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Public Utilities, Approved Return on Equity, Percentage Public Utilities, Approved Return on Equity, Percentage Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Depreciation Lives [Policy Text Block] depreciation lives [Policy Text Block] depreciation lives [Policy Text Block] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-Term Purchase Commitment, Category of Item Purchased [Domain] Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Common Stock, Shares Authorized Common Stock, Shares Authorized deferred income tax expense deferred income tax expense - footnote deferred income tax expense - footnote Ratio of Indebtedness to Net Capital Ratio of Indebtedness to Net Capital Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Transfers Into Level 3 Long-term Contract for Purchase of Electric Power [Line Items] Long-Term Contract for Purchase of Electric Power [Line Items] Defined Benefit Plan, Plan Assets, Payment for Settlement Defined Benefit Plan, Plan Assets, Payment for Settlement Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Other Commitment, Due in Fifth Year Other Commitment, to be Paid, Year Five Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Entity Voluntary Filers Entity Voluntary Filers First Mortgage Bonds - maximum rate First Mortgage Bonds - maximum rate First Mortgage Bonds - maximum rate Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits Defined Benefit Plan, Benefit Obligation, Special and Contractual Termination Benefits Defined Benefit Plan, Amortization of Gain (Loss) Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gain (Loss) Statement of Financial Position Location, Balance [Axis] Statement of Financial Position Location, Balance [Axis] Deferred income taxes Deferred Income Tax Expense (Benefit) Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Income Tax Uncertainties, Policy [Policy Text Block] Income Tax Uncertainties, Policy [Policy Text Block] Pension and other postretirement benefits Pension and Other Postretirement Benefits Cost (Reversal of Cost) Pension and Other Postretirement Benefits Cost (Reversal of Cost) Amounts written off, less recoveries Accounts Receivable, Allowance for Credit Loss, Writeoff Proceeds from Other Debt Proceeds from Other Debt Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Long-term Debt Total long-term debt Long-Term Debt Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Defined Benefit Plan, Plan Assets, Amount As of January 1 Defined Benefit Plan, Plan Assets, Amount Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Thereafter Long-Term Debt, Maturity, after Year Five Unfunded status of pension and postretirement plans Liability, Defined Benefit Pension Plan, Noncurrent Natural Gas Commodity Contract Asset, Current, Natural Gas Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to natural gas which are expected to be settled within a year or normal operating cycle, if longer. Electricity physical forward purchase Electricity physical forward purchase Electricity physical forward purchase Net actuarial loss (gain) included in comprehensive income Net actuarial loss (gain) included in comprehensive income The net increase or decrease of changes in the value of either the benefit obligation or the plan assets resulting from experience different from that assumed or from a change in an actuarial assumption, or the consequence of a decision to temporarily deviate from the substantive plan.included in comprehensive income Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Employee Stock Purchase Plan, Base Pay Threshold Employee Stock Purchase Plan, Base Pay Threshold Employee Stock Purchase Plan, Base Pay Threshold Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Document Annual Report Document Annual Report Finance Lease, Liability, Payments, Due Year Three Finance Lease, Liability, to be Paid, Year Three Decoupling mechanism deferrals, net of amortization Decoupling Mechanism Deferrals, Net The deferral, which can be either a positive or negaitive amount depending on whether a collection from or refund to customers results, of the amounts recorded in net income for energy useage by customers on a weather adjusted basis that is different from base rates as determined under the Company's decoupling mechanism, expected to be recovered or refunded in future periods. Prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax Vested, Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Domestic government, Debt securities US Government Securities, at Carrying Value Long-term Contract for Purchase of Electric Power [Domain] Long-Term Contract for Purchase of Electric Power [Domain] Defined Benefit Plan, Effect of Decrease of Rate of Return on Plan Assets on Service and Interest Cost Components Defined Benefit Plan, Effect of Decrease of Rate of Return on Plan Assets on Service and Interest Cost Components Defined Benefit Plan, Effect of Decrease of Rate of Return on Plan Assets on Service and Interest Cost Components Amortization of Intangible Assets Amortization of Intangible Assets Common Stock, No Par Value Common Stock, No Par Value Less: Unamortized debt expense Debt Instrument, Unamortized Discount Commitments and Contingencies, Policy [Policy Text Block] Commitments and Contingencies, Policy [Policy Text Block] Current Fiscal Year End Date Current Fiscal Year End Date Lessee, Operating Lease, Liability, Undiscounted Excess Amount Lessee, Operating Lease, Liability, Undiscounted Excess Amount Regulatory Asset [Domain] Regulatory Asset [Domain] PEO Name PEO Name Public Utilities, Allowance for Funds Used During Construction, Rate Public Utilities, Allowance for Funds Used During Construction, Rate Vesting [Axis] Vesting [Axis] Award Type [Domain] Award Type [Domain] Margin Deposit Assets Deposit Assets Shares issued pursuant to equity-based plans Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Noncurrent liability Liability, Defined Benefit Plan, Noncurrent Realized And Unrealized Losses Net Commodity Contracts, Foreign Currency Realized And Unrealized Gains And Losses Net Commodity Contracts, Foreign Currency Realized And Unrealized Gains And Losses Net Commodity Contracts, Foreign Currency Regulatory liabilities--noncurrent Regulatory Liability, Noncurrent Non-PEO NEO Non-PEO NEO [Member] Finance Lease, Liability, Payments, Due in Rolling Year Three Finance Lease, Liability, to be Paid, Rolling Year Three Finance lease obligations, net of current portion Finance Lease, Liability, Noncurrent Finance Lease, Liability, Noncurrent Increase (Decrease) in Contract with Customer, Asset Increase (Decrease) in Contract with Customer, Asset Employee Benefits Retirement Benefits [Text Block] Commercial [Member] Commercial [Member] Commercial [Member] Contingencies [Text Block] Contingencies Disclosure [Text Block] Unbilled Receivables, Current Unbilled Receivables, Current Regulatory Liability [Axis] Regulatory Liability [Axis] Long-term Debt Disclosure [Abstract] Long-term Debt Disclosure [Abstract] Long-term Debt Disclosure [Abstract] Class of Stock [Axis] Class of Stock [Axis] Revenue Bonds issued by the Public Utility Districts Revenue Bonds issued by the Public Utility Districts Revenue Bonds issued by the Public Utility Districts Deferred Tax Assets, Derivative Instruments Deferred Tax Assets, Derivative Instruments Finance Lease, Liability, Payments, Due Year Four Finance Lease, Liability, to be Paid, Year Four Finite-Lived Intangible Assets, Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Name Measure Name Entity Interactive Data Current Entity Interactive Data Current Equity Based Plans [Abstract] Equity Based Plans [Abstract] Employee stock purchase plans [Abstract] Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 Fair Value, Measurement with Unobservable Inputs Reconciliation, Liability, Transfers Into Level 3 Unrecorded Unconditional Purchase Obligation, Due after Five Years Unrecorded Unconditional Purchase Obligation, to be Paid, after Year Five Cash paid for income taxes Income Taxes Paid Deferred income taxes Deferred Tax Assets, Regulatory Assets and Liabilities Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Noncurrent Assets, Commodity Contracts: [Abstract] Noncurrent Assets, Commodity Contracts: [Abstract] Noncurrent Assets, Commodity Contracts: [Abstract] Maximum amount outstanding during the year Short-term Debt, Maximum amount outstanding during the year Short-term Debt, Maximum amount outstanding during the year Credit Derivatives Contract Type [Axis] Credit Derivatives Contract Type [Axis] Finance Lease, Liability, Payments, Due in Rolling Year Five Finance Lease, Liability, to be Paid, Rolling Year Five Share-based Payment Arrangement, Noncash Expense Share-Based Payment Arrangement, Noncash Expense Entity Number of Employees Entity Number of Employees Total deferred income tax assets Deferred Tax Assets, Net of Valuation Allowance Other Fair Value Measured at Net Asset Value Per Share [Member] Interest and Penalties Related to Income Taxes [Policy Text Block] interest and penalties related to income taxes [Policy Text Block] interest and penalties related to income taxes [Policy Text Block] Coal and transportationSupply Agreements [Member] Coal Supply Agreements [Member] Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Other income, net Nonoperating Income (Expense) SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Auditor Firm ID Auditor Firm ID Effective tax rate Effective Income Tax Rate Reconciliation, Percent Income from operations Operating Income (Loss) Operating Income (Loss) Purchases of nuclear decommissioning trust securities Payments to Acquire Investments to be Held in Decommissioning Trust Fund Total liabilities and shareholders' equity Liabilities and Equity Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Fair Value Hierarchy and NAV [Axis] Defined Benefit Plan, Fair Value of Plan Assets by Measurement [Axis] Fair Value Hierarchy and NAV [Axis] Public Utilities, Property, Plant and Equipment, Common Public Utilities, Property, Plant and Equipment, Common Marketable Securities, Policy [Policy Text Block] Marketable Securities, Policy [Policy Text Block] Defined Benefit Plan, Equity Securities, Non-US Defined Benefit Plan, Equity Securities, Non-US [Member] Liabilities from price risk management activities-current Derivative Liability, Current Risk Management Derivative Instruments and Hedging Activities Disclosure [Text Block] Finance Lease, Liability, Payments, Due Year Two Finance Lease, Liability, to be Paid, Year Two Commodity [Domain] Commodity [Domain] [Domain] for Commodity [Axis] Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] Dividends paid Payments of Dividends FinanceLeaseCost FinanceLeaseCost Total Finance Lease Cost Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Maturities of Long-Term Debt [Table Text Block] Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Fair Value of Financial Instruments Note [Abstract] Fair Value of Financial Instruments Note [Abstract] Fair value of financial instruments note. Underlying Security Market Price Change Underlying Security Market Price Change, Percent Expected return on plan assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Individual: Individual [Axis] Share-based Payment Arrangement, Decrease for Tax Withholding Obligation Share-Based Payment Arrangement, Decrease for Tax Withholding Obligation Asset Retirement Obligation, Current Asset Retirement Obligation, Current Construction work-in-progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] AOCI Attributable to Parent [Member] Schedule of Long-term Contracts for Purchase of Electric Power [Table Text Block] Schedule of Long-Term Contracts for Purchase of Electric Power [Table Text Block] Schedule of Regulatory Assets [Table Text Block] Schedule of Regulatory Assets [Table Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Product and Service [Axis] Product and Service [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Number of Union Employees Number of Union Employees Number of employees subject to collective bargaining agreements. Statement [Line Items] Statement [Line Items] Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block] Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block] Lointly-owned plant [Abstract] Lointly-owned plant [Abstract] Lointly-owned plant [Abstract] Defined Benefit Plan, Plan Assets, Benefits Paid Defined Benefit Plan, Plan Assets, Benefits Paid Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Regulatory Assets and Liabilities Disclosure [Abstract] Regulatory Assets and Liabilities Disclosure [Abstract] Deferred: Deferred: [Abstract] Deferred: [Abstract] Derivatives, Policy [Policy Text Block] Derivatives, Policy [Policy Text Block] Loss Contingency, Range of Possible Loss, Maximum Loss Contingency, Estimate of Possible Loss Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Defined Benefit Plan, Plan Assets, Administration Expense Defined Benefit Plan, Plan Assets, Administration Expense Minimum [Member] Minimum [Member] reductioninprovisionoffsetinregulatoryassets reductioninprovisionoffsetinregulatoryassets Reduction in provision off set in regulatory assets due to Covid-19 deferral accounting. Unamortized Debt Issuance Expense Unamortized Debt Issuance Expense Adoption Date Trading Arrangement Adoption Date Increase in provision Accounts Receivable, Credit Loss Expense (Reversal) In service Public Utilities, Property, Plant and Equipment, Plant in Service Public Utilities, Property, Plant and Equipment, Plant in Service 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] Employee Stock Purchase Plan, Number of Available Shares Employee Stock Purchase Plan, Number of Available Shares Employee Stock Purchase Plan, Number of Available Shares Federal statutory tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Derivative, by Nature [Axis] Derivative Instrument [Axis] Derivative Instrument [Axis] Exercise Price Award Exercise Price Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Employee Stock Purchase Plan, Share Purchase Limitation Employee Stock Purchase Plan, Share Purchase Limitation Employee Stock Purchase Plan, Share Purchase Limitation Regulated and Unregulated Operating Revenue Regulated and Unregulated Operating Revenue Arrangement Duration Trading Arrangement Duration Schedule of Asset Retirement Obligations [Table Text Block] Schedule of Asset Retirement Obligations [Table Text Block] Lessee, Finance Leases [Text Block] Lessee, Finance Leases [Text Block] Shareholders’ equity: Equity, Attributable to Parent [Abstract] Name of Property [Axis] Name of Property [Axis] Regulatory assets Deferred Tax Liabilities, Regulatory Assets Commodity contracts: Unrealized Gain (Loss) on Derivatives and Commodity Contracts [Abstract] Natural gas Commodity Contract Asset, Natural gas Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to purchases or sales of natural gas. Trojan decommissioning activities Trojan decommissioning activities Asset retirement obligation related to Trojan decommissioning activities Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Fair Value Transfer, Policy Fair Value Transfer, Policy [Policy Text Block] Finance Lease, Liability Finance Lease, Liability Finance Lease, Liability Future Amortization Expense, Year Four Finite-Lived Intangible Asset, Expected Amortization, Year Four All Individuals All Individuals [Member] Balance Sheet Compnents [Abstract] Balance Sheet Compnents [Abstract] Balance Sheet Compnents [Abstract] Total current derivative assets Current Derivative Assets Fair valules as of the balance sheet date for all assets resulting from contracts that meet the criteria of being accounted for as derivative instruments, and which are expected to be settled within one year or the normal operating cycle, if longer. Depreciation expense rate Depreciation expense rate Depreciation expense rate as a percent of the related average depreciable plant in service. Schedule of Other Assets and Other Liabilities [Table Text Block] Schedule of Other Assets and Other Liabilities [Table Text Block] Other Investments Other Investments Miscellaneous income, net Other Nonoperating Income (Expense) Other Postretirement Benefit Plans [Domain] Other Postretirement Benefit Plans [Member] Other Postretirement Benefit Plans [Member] Other Postretirement Benefits Plan [Member] PGE Share of Capacity PGE portion of Capacity PGE portion of Capacity from Public Utility Districts Electricity Realized and Unrealized Gains and Losses, Net, Commodity Contracts, Electricity Realized and unrealized gains and losses, net on commodity contracts related to electricity not designated as hedging instruments included in purchased power and fuel expense in the statement of income. Proceeds from issuance of shares pursuant to equity-based plans Proceeds, Issuance of Shares, Share-Based Payment Arrangement, Including Option Exercised Income Taxes [Abstract] Income Taxes [Abstract] Income Taxes [Abstract] Net realized and unrealized losses Realized and Unrealized Gains and Losses, Net, Commodity Contract Realized and Unrealized Gains and Losses, Net, Commodity Contracts Other Other Current Liabilities - Other Other Current Liabilities - Other Generation, transmission and distribution Utilities Operating Expense, Maintenance and Operations Current liability Liability, Defined Benefit Plan, Current Assumptions used: Defined Benefit Plan, Assumptions Used in Calculations [Abstract] Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Fair value of plan assets: Assets, Fair Value Disclosure [Abstract] Spent Nuclear Fuel Obligation, Noncurrent Spent Nuclear Fuel Obligation, Noncurrent Dividend Reinvestment and Direct Stock Purchase Plan Shares Dividend Reinvestment and Direct Stock Purchase Plan Shares Represents common shares set aside, issued and available for issue related to the Dividend Reinvestment and Direct Stock Purchase Plan Accounts payable Accounts Payable and Accrued Liabilities, Current Long-term Purchase Commitment [Line Items] Long-Term Purchase Commitment [Line Items] Financial Instruments, Owned, at Fair Value Financial Instruments, Owned, at Fair Value Deferred income taxes Deferred Income Tax Liabilities, Net Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Share-Based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block] Stock Repurchased During Period, Shares Stock Repurchased During Period, Shares Commitments [Member] Commitments [Member] Net actuarial loss Net actuarial loss Net actuarial loss from Defined Benefit Plans included in Accumulated Other Comprehensive Income. Other, net Increase (Decrease) in Other Operating Assets Total derivative liabilities Derivative Liabilities, Total Fair values as of the balance sheet date of all liabilities resulting from contracts that meet the criteria of being accounted for as derivative instruments. Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Federal Deferred Federal Income Tax Expense (Benefit) Assets and Liabilities associated with Non Qualified Benefit Plans [Table Text Block] Assets and Liabilities associated with Non Qualified Benefit Plans [Table Text Block] Assets and Liabilities associated with Non Qualified Benefit Plans [Table Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Public Utilities, Property, Plant and Equipment, General Public Utilities, Property, Plant and Equipment, General Public Utilities, Property, Plant and Equipment, General Measure: Measure [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Asset Class [Domain] Preferred Stock, Shares Authorized Preferred Stock, Shares Authorized Stock Issued During Period, Shares, New Issues Stock Issued During Period, Shares, New Issues Defined Benefit Plan, Expected Future Benefit Payments in Year One Defined Benefit Plan, Expected Future Benefit Payment, Year One Entity Emerging Growth Company Entity Emerging Growth Company Liabilities, Fair Value Disclosure Liabilities, Fair Value Disclosure 2027 Long-Term Debt, Maturity, Year Five Fair Value Option, Disclosures [Table] Fair Value Option, Disclosures [Table] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Regulated Operating Revenue Regulated Operating Revenue Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Minimum Finance Lease, Right-of-Use Asset Finance Lease, Right-of-Use Asset, after Accumulated Amortization Equity Component [Domain] Equity Component [Domain] Electricity [Member] Electricity [Member] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Entity Shell Company Entity Shell Company Commodity Contract Asset, Noncurrent, Natural Gas Commodity Contract Asset, Noncurrent, Natural Gas Carrying amount as of the balance sheet date of the asset arising from commodity contracts related to natural gas which are expected to be settled after a year or beyond the normal operating cycle, if longer. Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Defined Benefit Plan, Expected Future Benefit Payments in Year Four Defined Benefit Plan, Expected Future Benefit Payment, Year Four Gain on Derivative Instruments, Pretax Gain on Derivative Instruments, Pretax SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] Statement [Table] Statement [Table] Interest Expense, Debt Interest Expense, Debt Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items] Deferred Revenue, Revenue Recognized Deferred Revenue, Revenue Recognized Derivatives Not Designated as Hedging Instruments [Table Text Block] Derivatives Not Designated as Hedging Instruments [Table Text Block] Cash paid for interest, net of amounts capitalized Interest Paid, Excluding Capitalized Interest, Operating Activities Non-qualified benefit plan trust Noncurrent asset Asset, Held-in-Trust, Noncurrent Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Foreign currency exchange Volume Related to Derivative Instruments Held at Balance Sheet Date, Foreign Currency Net amount associated with the reporting entity's derivative instruments recorded as of the balance sheet date having arisen from price risk management activities related to foreign currency. Total current assets Assets, Current Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Excise Taxes Collected Excise Taxes Collected 2025 Long-Term Debt, Maturity, Year Three 2059 Member 2059 Member [Member] 2059 Member Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Company contributions Defined Benefit Plan, Plan Assets, Contributions by Employer Unrecorded Unconditional Purchase Obligation Unrecorded Unconditional Purchase Obligation Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Change in Accounting Estimate, Type [Domain] Change in Accounting Estimate, Type [Domain] Income Taxes Income Tax Disclosure [Text Block] Lessee, Operating Lease, Liability, Payments, Due Year Four Lessee, Operating Lease, Liability, to be Paid, Year Four Capital Addition Purchase Commitments [Member] Capital Addition Purchase Commitments [Member] Public Utility Districts [Member] Public Utility Districts [Member] Future Minimum payments to Public Utility Districts for purchase obligations [Member] Debt, Policy [Policy Text Block] Debt, Policy [Policy Text Block] Operating Lease, Weighted Average Discount Rate, Percent Operating Lease, Weighted Average Discount Rate, Percent Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities JosephR.Trpik [Member] JosephR.Trpik Credit Facility [Axis] Credit Facility [Axis] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency Nature [Axis] Long-term Debt, Fair Value Long-Term Debt, Fair Value Entity Registrant Name Entity Registrant Name Materials and supplies Other Inventory, Supplies, Gross Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Finance Lease, Liability, Payments, Due in Rolling Year Four Finance Lease, Liability, to be Paid, Rolling Year Four Depreciation and amortization Depreciation, Depletion and Amortization Estimated average service lives [Table Text Block] Estimated average service lives [Table Text Block] Estimated average service lives [Table Text Block] State and local Deferred State and Local Income Tax Expense (Benefit) Fair Value as of Grant Date Award Grant Date Fair Value Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Deferred Purchased Power Costs Deferred Purchased Power Costs Disaggregation of Revenue [Table Text Block] Disaggregation of Revenue [Table Text Block] Deferred Tax Assets, tax credits, net of valuation allowance Deferred Tax Assets, tax credits, net of valuation allowance The sum of the tax effects as of the balance sheet date of the amount of tax credits available for future use, net of any valuation allowance. Environmental Restoration Costs [Member] Environmental Restoration Costs [Member] Asset Retirement Obligation Disclosure [Abstract] Asset Retirement Obligation Disclosure [Abstract] Consolidation, Policy [Policy Text Block] Consolidation, Policy [Policy Text Block] Debt securities - domestic government debt securities - domestic government debt securities - domestic government Restatement Determination Date: Restatement Determination Date [Axis] Title of 12(b) Security Title of 12(b) Security Common stock, no par value, 160,000,000 shares authorized; 89,283,353 and 89,410,612 shares issued and outstanding as of December 31, 2022 and 2021, respectively Common Stock, Value, Issued Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] Finance Lease, Interest Payment on Liability Finance Lease, Interest Payment on Liability Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Classification in consolidated balance sheet: Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position [Abstract] Share-based Payment Arrangement [Abstract] Share-Based Payment Arrangement [Abstract] Asset Retirement Obligation Asset Retirement Obligation Asset Retirement Obligation Asset Retirement Obligation Basis of Presentation [Abstract] Basis of Presentation [Abstract] Basis of Presentation [Abstract] Regulatory assets--noncurrent Regulatory Asset, Noncurrent State and local taxes, net of federal tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Regulatory Liability, Current Regulatory Liability, Current Contingencies [Abstract] Contingencies [Abstract] Contingencies [Abstract] Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Defined Benefit Plan, Expected Future Benefit Payments in Year Five Defined Benefit Plan, Expected Future Benefit Payment, Year Five Preferred stock, no par value, 30,000,000 shares authorized; none issued and outstanding Preferred Stock, Value, Issued Regulatory Liabilities Regulatory Liability Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Deferred Tax Liabilities, Gross, Noncurrent Deferred Tax Liabilities, Gross Average daily amount of short-term debt outstanding Short-Term Debt, Average Outstanding Amount Basic Earnings Per Share, Basic Operating Lease, Payments Operating Lease, Payments Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Payments for Environmental Liabilities Payments for Environmental Liabilities Gross Reporting of Positive and Negative Exposures Related to Derivative Instruments [Policy Text Block] Gross Reporting of Positive and Negative Exposures Related to Derivative Instruments [Policy Text Block] The company elects to report gross on the balance sheet the positive and negative exposures resultinig from derivative instruments. Defined Benefit Plan, Benefit Obligation, Changes Between Actual and Expected Return on Plan Assets, Gains Defined Benefit Plan, Benefit Obligation, Changes Between Actual and Expected Return on Plan Assets, Gains Defined Benefit Plan, Benefit Obligation, Changes Between Actual and Expected Return on Plan Assets, Gains Number of Retail Customers Number of Retail Customers Includes residential, commercial and industrial. Accrued capital additions Capital Expenditures Incurred but Not yet Paid Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment, Policy [Policy Text Block] Total current liabilities Liabilities, Current Proceeds from Issuance of Commercial Paper Proceeds from Issuance of Commercial Paper Public Utilities, Property, Plant and Equipment, Transmission Public Utilities, Property, Plant and Equipment, Transmission Future Amortization Expense, Year One Finite-Lived Intangible Asset, Expected Amortization, Year One Line of Credit Facility, Amount Outstanding Long-Term Line of Credit Granted, Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Contribution to non-qualified employee benefit trust Increase (Decrease) in Deferred Compensation Other comprehensive income (loss)- Change in compensation retirement benefits liability and amortization, net of taxes of an immaterial amount in all three years Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Credit Facilities Revolving Credit Facilities [Text Block] Revolving Credit Facilities [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Money market funds Private Equity Funds [Member] Discount rate used to calculate benefit obligation Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Total Revenues Revenues Unregulated Operating Revenue Unregulated Operating Revenue Notes Payable to Banks [Member] Notes Payable to Banks [Member] Share-based Payment Arrangement [Text Block] Share-Based Payment Arrangement [Text Block] Entity Address, City or Town Entity Address, City or Town Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Proceeds from Issuance of Long-Term Debt Lessee, Leases [Policy Text Block] Lessee, Leases [Policy Text Block] Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment Asset Retirement Obligation [Policy Text Block] Asset Retirement Obligation [Policy Text Block] Assets and Liabilites associated with Non-qualified Benefit Plans [Table] Assets and Liabilites associated with Non-qualified Benefit Plans [Table] Assets and Liabilites associated with Non-qualified Benefit Plans [Table] Operating Lease, Liability, Related to Power Purchase Agreements Operating Lease, Liability, Related to Power Purchase Agreements Operating Lease, Liability, Related to Power Purchase Agreements 401k Plan Company contributions Defined Contribution Plan, Employer Discretionary Contribution Amount Loss Contingencies [Table] Loss Contingencies [Table] Forfeited, Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period EPA Investigation of Portland Harbor [Member] EPA Investigation of Portland Harbor [Member] EPA Investigation of Portland Harbor 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] Electricity Commodity Contract Liability, Current, Electricity Carrying amount as of the balance sheet date of the liability arising from commodity contracts related to electricity which are expected to be settled within a year or the normal operating cycle, if longer. Regulatory Assets and Liabilities [Abstract] Regulatory Assets and Liabilities [Abstract] Regulatory Assets and Liabilities [Abstract] Revenue from Contract with Customer [Text Block] Revenue from Contract with Customer [Text Block] Document Fiscal Year Focus Document Fiscal Year Focus Employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Assets from price risk management activities Regulatory assets from price risk management activities Regulatory assets from price risk management activities Public Utilities, Property, Plant and Equipment, Generation or Processing Public Utilities, Property, Plant and Equipment, Generation or Processing Assets, Fair Value Disclosure Assets, Fair Value Disclosure Future Amortization Expense, Year Five Finite-Lived Intangible Asset, Expected Amortization, Year Five Document Period End Date Document Period End Date Current portion of long-term debt Finance Lease, Liability, Current Finance Lease, Liability, Current commitment costs commitment costs commitment costs of contracts with the Public Utility Districts Lessee, Operating Lease, Liability, Payments, Due Lessee, Operating Lease, Liability, Payments, Due Lessee, Operating Lease, Liability, to be Paid Domestic Equity Securities Domestic Equity Securities Domestic Equity Securities Outstanding, Units Outstanding, Units Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Fair Value by Asset Class [Axis] Asset Class [Axis] Insider Trading Arrangements [Line Items] Wind estimated average service life - wind production plant estimated average service life - wind production plant 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] Lessee, Operating Lease, Liability, Payments, Due Year Three Lessee, Operating Lease, Liability, to be Paid, Year Three Long-term Contracts for Purchase of Electric Power [Table] Regulated Operation, Long-Term Contract for Purchase of Electric Power [Table] Defined Benefit Plan, Accumulated Benefit Obligation Defined Benefit Plan, Accumulated Benefit Obligation Other Contract [Member] Other Contract [Member] Allowance for Funds Used During Construction, Policy [Policy Text Block] Allowance for Funds Used During Construction, Policy [Policy Text Block] lower range of costs lower range of costs lower range of costs Document Transition Report Document Transition Report Effective Income Tax Rate Reconciliation, Tax Credit, Percent Effective Income Tax Rate Reconciliation, Tax Credit, Percent Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Revenue, Transaction Price Measurement, Tax Exclusion [Policy Text Block] Revenue, Transaction Price Measurement, Tax Exclusion [Policy Text Block] Entity Current Reporting Status Entity Current Reporting Status Retained Earnings Retained Earnings [Member] General Public Utilities, Property, Plant and Equipment, Common, Useful Life Litigation Settlement, Fee Expense Litigation Settlement, Fee Expense Trust [Axis] Trust [Axis] Trust Investments [Axis] Other Commitment, Due after Fifth Year Other Commitment, to be Paid, after Year Five Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Executive Category: Executive Category [Axis] Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Letter of Credit [Member] Letter of Credit [Member] Company Selected Measure Name Company Selected Measure Name