Summary of Significant Accounting Policies [Abstract] Summary of Significant Accounting Policies [Abstract] Schedule of Property, Plant and Equipment [Table] Schedule of Property, Plant and Equipment [Table] Regulatory Asset [Axis] Regulatory Asset [Axis] Regulatory Asset [Domain] Regulatory Asset [Domain] Noncurrent Regulatory Assets [Member] Noncurrent Regulatory Assets [Member] Noncurrent Regulatory Assets Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment, Type [Domain] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Other Investments Other Investments Margin deposit Margin Deposit Assets Letters of Credit Outstanding, Amount Letters of Credit Outstanding, Amount Public Utilities, Allowance for Funds Used During Construction, Rate Public Utilities, Allowance for Funds Used During Construction, Rate Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest Public Utilities, Allowance for Funds Used During Construction, Capitalized Interest Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Depreciation expense rate Depreciation expense rate Depreciation expense rate as a percent of the related average depreciable plant in service. asset retirement removal costs included in depreciation expense asset retirement removal costs included in depreciation expense asset retirement removal costs included in depreciation expense Finite-Lived Intangible Assets, Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Amortization of Intangible Assets Amortization of Intangible Assets Future Amortization Expense, Year One Future Amortization Expense, Year One Future Amortization Expense, Year Two Future Amortization Expense, Year Two Future Amortization Expense, Year Three Future Amortization Expense, Year Three Future Amortization Expense, Year Four Future Amortization Expense, Year Four Future Amortization Expense, Year Five Future Amortization Expense, Year Five 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. 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. net variable power cost underrun net variable power cost underrun Amount by which net variable power costs underrun the baseline net variable power cost established under the Company's annual update tarrif. net variable power cost savings outside of threshold net variable power cost savings outside of threshold Amount by which net variable power costs were below the lower threshold of the deadband range established under the Company's annual update tariff. Estimated Refund Under Power Cost Adjustment Mechanism Estimated Refund Under Power Cost Adjustment Mechanism Estimated Refund Under Power Cost Adjustment Mechanism reduction in potential refund under PCAM reduction in potential refund under PCAM Reduction in potential refund to customers under the Company's Power Cost Adjustment Mechanism due to the Regulated Earnings Test. potential refund under the PCAM potential refund under the PCAM Potential refund to customers under the Company's Power Cost Adjustment Mechanism. net variable power cost overrun net variable power cost overrun Amount by which the actual net variable power cost exceeded the baseline net variable power costs established under the Company's annual update tariff. Franchise taxes Franchise taxes Franchise taxes collected from customers and remitted to local taxing jurisdictions. Deferred Tax Assets, Regulatory Assets and Liabilities Deferred Tax Assets, Regulatory Assets and Liabilities Employee Benefits [Abstract] Employee Benefits [Abstract] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Pension Plans, Defined Benefit [Member] Pension Plans, Defined Benefit [Member] Other Postretirement Benefit Plans [Member] Other Postretirement Benefit Plans, Defined Benefit [Member] Non Qualified Benefit Plans [Member] Non Qualified Benefit Plans [Member] Non Qualified Benefit Plans [Member] Defined Benefit Plan by Plan Asset Categories [Axis] Defined Benefit Plan by Plan Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Defined Benefit Plan, Fair Value of Plan Assets by Measurement [Axis] Defined Benefit Plan, Fair Value of Plan Assets by Measurement [Axis] Fair Value Plan Asset Measurement [Domain] Fair Value Plan Asset Measurement [Domain] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan, Expected Future Benefit Payments in Year One Defined Benefit Plan, Expected Future Benefit Payments in Year One Defined Benefit Plan, Expected Future Benefit Payments in Year Two Defined Benefit Plan, Expected Future Benefit Payments in Year Two Defined Benefit Plan, Expected Future Benefit Payments in Year Three Defined Benefit Plan, Expected Future Benefit Payments in Year Three Defined Benefit Plan, Expected Future Benefit Payments in Year Four Defined Benefit Plan, Expected Future Benefit Payments in Year Four Defined Benefit Plan, Expected Future Benefit Payments in Year Five Defined Benefit Plan, Expected Future Benefit Payments in Year Five Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter Defined Benefit Plan, Expected Future Benefit Payments in Five Fiscal Years Thereafter Price Risk Management [Abstract] Price Risk Management [Abstract] Derivative [Table] Derivative [Table] Derivative, by Nature [Axis] Derivative, by Nature [Axis] Derivative, Name [Domain] Derivative, Name [Domain] Derivative [Line Items] Derivative [Line Items] Commodity contracts: [Abstract] Commodity contracts: [Abstract] 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 arisn from price risk management activities. Volume Related to Derivative Instruments at Balance Sheet Date Commodity Contracts 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. Variable Interest Entities Note [Abstract] Variable Interest Entities Note [Abstract] Variable Interest Entities VariableInterestEntities [Text Block] VariableInterestEntities [Text Block] NOTE 7: ASSET RETIREMENT OBLIGATIONS [Abstract] NOTE 7: ASSET RETIREMENT OBLIGATIONS [Abstract] Asset Retirement Obligations, Policy [Policy Text Block] Asset Retirement Obligations, Policy [Policy Text Block] Earnings Per Share [Abstract] Earnings Per Share Earnings Per Share [Text Block] Jointly-owned Plant Note [Abstract] Jointly-owned Plant Note [Abstract] Jointly-owned Plant [Text Block] Jointly-owned Plant [Text Block] Jointly-owned Plant [Text Block] Service cost Defined Benefit Plan, Service Cost Interest cost on benefit obligation Defined Benefit Plan, Interest Cost Expected return on plan assets Defined Benefit Plan, Expected Return on Plan Assets Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of net actuarial loss Defined Benefit Plan, Amortization of Gains (Losses) Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost Long-term Debt Disclosure [Abstract] Long-term Debt Disclosure [Abstract] Long-term Debt Long-term Debt [Text Block] Balance Sheet Components [Abstract] Balance Sheet Components [Abstract] Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Investments held in trust [Table Text Block] investments held in trust [Table Text Block] investments held in trust [Table Text Block] Schedule of Other Assets and Other Liabilities [Table Text Block] Schedule of Other Assets and Other Liabilities [Table Text Block] Fair Value of Financial Instruments [Abstract] Fair Value of Financial Instruments [Abstract] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Trust [Axis] Trust [Axis] Trust Investments [Axis] Trust [Domain] Trust [Domain] Trust [Domain] Fair Value by Measurement Frequency [Axis] Fair Value by Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value, Measurements, Fair Value Hierarchy [Domain] Estimate of Fair Value, Fair Value Disclosure [Member] Estimate of Fair Value, Fair Value Disclosure [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] 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] Money market funds Money Market Funds, at Carrying Value Domestic government, Debt securities US Government Securities, at Carrying Value Corporate debt securities held in decommissioning trust assets Corporate debt securities held in decommissioning trust assets Corporate debt securities held in decommissioning trust assets Corporate Credit, Debt securities Financial Instruments, Owned, Corporate Debt, at Fair Value Domestic Equity Securities Domestic Equity Securities Domestic Equity Securities International Equity Securities International equity securities International equity securities Debt securities - domestic government debt securities - domestic government debt securities - domestic government 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. 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. Financial Instruments, Owned, at Fair Value Financial Instruments, Owned, at Fair Value Liabilities from price risk management activities: [Abstract] Liabilities from price risk management activities: [Abstract] Liabilities from price risk management activities: [Abstract] 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. 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. Liabilities, Fair Value Disclosure Liabilities, Fair Value Disclosure Insurance contracts, at cash surrender value Cash Surrender Value, Fair Value Disclosure Income Taxes [Abstract] Income Taxes [Abstract] Operating Loss Carryforwards [Table] Operating Loss Carryforwards [Table] Income Tax Authority [Axis] Income Tax Authority [Axis] Income Tax Authority [Domain] Income Tax Authority [Domain] Operating Loss Carryforwards [Line Items] Operating Loss Carryforwards [Line Items] Deferred Taxes Reclass, To Depreciation and Amortization From Regulatory Liabilities Deferred Taxes Reclass, To Depreciation and Amortization From Regulatory Liabilities Reclass of within deferred income taxes to Depreciation and Amortization from Regulatory Liabilities to conform with current year presentation. Deferred Taxes Reclass, To Price Risk Management From Regulatory Liabilities Deferred Taxes Reclass, To Price Risk Management From Regulatory Liabilities Reclass within deferred income taxes to Price Risk Management from Regulatory Liabilities to conform with the current year presentation. Deferred Taxes Reclass, To Employee Benefits From Regulatory Assets Deferred Taxes Reclass, To Employee Benefits From Regulatory Assets Reclass of deferred income taxes to Employee Benefits from Regulatory Assets to conform with current year presentation. Deferred Taxes Reclass To Regulatory Assets From Other Deferred Taxes Reclass To Regulatory Assets From Other Reclass of deferred income taxes to regulatory assets from other to conform with current year presentation. Loss Carryforward, Federal Loss Carryforward, Federal Federal operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws Loss Carryforward, State Loss Carryforward, State State operating loss, before tax effects, available to reduce future taxable income under enacted tax laws. 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. Tax Credit Carryforward, State Tax Credit Carryforward, State The amount of the state tax credit carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Deferred Tax Assets, Valuation Allowance Deferred Tax Assets, Valuation Allowance Valuation Allowance, Deferred Tax Asset, Change in Amount Valuation Allowance, Deferred Tax Asset, Change in Amount Unrecognized Tax Benefits Unrecognized Tax Benefits Unrecognized Tax Benefits, Interest on Income Taxes Expense Unrecognized Tax Benefits, Interest on Income Taxes Expense Unrecognized Tax Benefits, Income Tax Penalties Expense Unrecognized Tax Benefits, Income Tax Penalties Expense Unrecognized Tax Benefits, Decreases Resulting from Current Period Tax Positions Unrecognized Tax Benefits, Decreases Resulting from Current Period Tax Positions Valuation Allowances and Reserves, Deductions Valuation Allowances and Reserves, Deductions Earnings Per Share, Policy [Policy Text Block] Earnings Per Share, Policy [Policy Text Block] Asset Retirement Obligation Disclosure [Abstract] Schedule of Asset Retirement Obligations [Table Text Block] Schedule of Asset Retirement Obligations [Table Text Block] Schedule of Change in Asset Retirement Obligation [Table Text Block] Schedule of Change in Asset Retirement Obligation [Table Text Block] Revolving Credit Facilities [Abstract] Revolving Credit Facilities [Abstract] Schedule of Short-term Debt [Table Text Block] Schedule of Short-term Debt [Table Text Block] Valuation Allowance, Commentary Valuation Allowance, Commentary Regulatory Assets and Liabilities [Abstract] Regulatory Assets and Liabilities [Abstract] Description of Impairment to Carrying Amount of Regulatory Assets Description of Impairment to Carrying Amount of Regulatory Assets Refund Period Not Yet Determined for REgulatory Liabilities, PCAM and Pollution Control Tax Credits Refund Period Not Yet Determined for REgulatory Liabilities, PCAM and Pollution Control Tax Credits Refund Period Not Yet Determined for REgulatory Liabilities, PCAM and Pollution Control Tax Credits Remaining Recovery Period of Regulatory Asset, Pension and Postretirement Plans, For Which No Return on Investment During Recovery is Provided Remaining Recovery Period of Regulatory Asset, Pension and Postretirement Plans, For Which No Return on Investment During Recovery is Provided Remaining Recovery Period of Regulatory Asset, Pension and Postretirement Plans, For Which No Return on Investment During Recovery is Provided Remaining Refund Period of Regulatory Liabilities, Asset Removal Costs and Retirement Obligations Remaining Refund Period of Regulatory Liabilities, Asset Removal Costs and Retirement Obligations Remaining Refund Period of Regulatory Liabilities, Asset Removal Costs and Retirement Obligations Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Estimated average service lives [Table Text Block] Estimated average service lives [Table Text Block] Estimated average service lives [Table Text Block] Fair Value of Financial Instruments Note [Abstract] Fair value of financial instruments note. Fair Value of FInancial Instruments Fair Value Disclosures [Text Block] Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Credit Facilities - $370 million revolver Credit Facilities - $370 million revolver Credit Facilities - $370 million revolver, with $10 million scheduled to terminate in July 2012 and $360 million scheduled to terminate in July 2013. Portion of $370 million credit facility scheduled to terminate in July 2012 Portion of $370 million credit facility scheduled to terminate in July 2012 Portion of $370 million credit facility scheduled to terminate in July 2012 Portion of $370 million credit facility scheduled to terminate in July 2013 Portion of $370 million credit facility scheduled to terminate in July 2013 Portion of $370 million credit facility scheduled to terminate in July 2013 Credit Facilities - $300 million revolver Credit Facilities - $300 million revolver Credit Facilities - $300 million revolver Line of Credit Facitlity, Covenant Terms, One Month Term Line of Credit Facitlity, Covenant Terms, One Month Term Line of Credit Facitlity, Covenant Terms, One Month Term Line of Credit Facitlity, Covenant Terms, Two Month Term Line of Credit Facitlity, Covenant Terms, Two Month Term Line of Credit Facitlity, Covenant Terms, Two Month Term Line of Credit Facitlity, Covenant Terms, Three Month Term Line of Credit Facitlity, Covenant Terms, Three Month Term Line of Credit Facitlity, Covenant Terms, Three Month Term Line of Credit Facitlity, Covenant Terms, Six Month Term Line of Credit Facitlity, Covenant Terms, Six Month Term Line of Credit Facitlity, Covenant Terms, Six Month Term Debt Instrument, Covenant Description Debt Instrument, Covenant Description Ratio of Indebtedness to Net Capital Ratio of Indebtedness to Net Capital Commercial Paper, Maximum Term Commercial Paper, Maximum Term Commercial Paper, Maximum Term 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 Short-term Debt Short-term Debt Commercial Paper Commercial Paper Line of Credit Facility, Amount Outstanding Line of Credit Facility, Amount Outstanding Line of Credit Facility, Remaining Borrowing Capacity Line of Credit Facility, Remaining Borrowing Capacity Regulatory Assets and Liabilities Disclosure [Abstract] Regulatory Assets Earning a Return, Other Category Regulatory Assets Earning a Return, Other Category Regulatory assets in 'other' category earning a rate of return. Regulatory Assets Earning a Return Regulatory Assets Earning a Return Regulatory assets earning a rate of return. Regulatory Assets Earning a Rate of Return at the Cost of Capital Regulatory Assets Earning a Rate of Return at the Cost of Capital Regulatory assets earning a rate of return at the cost of capital. Authorized Cost of Capital Authorized Cost of Capital Authorized cost of capital rate. 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. Approved Rate for Deferred Account Under Amortization, Low End of Range Approved Rate for Deferred Account Under Amortization, Low End of Range Low end of the range of approved rates of return for amortizing deferred accounts (regulatory assets). Approved Rate for Deferred Accounts under Amortization, High End of Range Approved Rate for Deferred Accounts under Amortization, High End of Range High end of the range of approved rates of return for amortizing deferred accounts (regulatory assets). Regulatory Assets Earning a Rate of Return by Inclusion in Rate Base Regulatory Assets Earning a Rate of Return by Inclusion in Rate Base Regulatory assets earning a rate of return by inclusion in rate base. Amount of Impairment to Carrying Amount of Regulatory Assets Amount of Impairment to Carrying Amount of Regulatory Assets Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Net of Forfeitures [Abstract] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Outstanding, Units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number 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 Granted, Units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period 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 Forfeited, Units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Forfeited, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period, Weighted Average Grant Date Fair Value Vested, Units Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period 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 Outstanding, Units Outstanding, Weighted Average Grant Date Fair Value Contingencies [Abstract] Contingencies [Abstract] Loss Contingencies [Table] Loss Contingencies [Table] Loss Contingencies by Nature of Contingency [Axis] Loss Contingencies by Nature of Contingency [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Loss Contingencies [Line Items] Loss Contingencies [Line Items] investment in Trojan investment in Trojan The portion of the Company's remaining investment in its Trojan plant that the OPUC allowed the Company to recover. Customer refund for Trojan Investment, net of Interest Customer refund for Trojan Investment, net of Interest Refund to customers for Trojan Investment, net of Interest Interest Rate Applied to Trojan Refund Interest Rate Applied to Trojan Refund Interest Rate Applied to Trojan Refund refund to customers for Trojan Investment including interest refund to customers for Trojan Investment including interest refund to customers for Trojan Investment including interest Class action damages sought Class action damages sought Class action damages sought by plaintiffs against the Company in regard to return on its investment in Trojan. Site Contingency, Names of Other Potentially Responsible Parties Site Contingency, Names of Other Potentially Responsible Parties river miles river miles river miles Repayments of Pollution Control Bond Repayments of Pollution Control Bond Long-term Debt, Unclassified [Abstract] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Maturities of Long-term Debt [Table Text Block] Schedule of Maturities of Long-term Debt [Table Text Block] Commitmtents and Guarantees [Abstract] Commitmtents and Guarantees [Abstract] Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation [Table] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unrecorded Unconditional Purchase Obligation by Category of Item Purchased [Axis] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] Unrecorded Unconditional Purchase Obligation [Line Items] Unrecorded Unconditional Purchase Obligation [Line Items] percentage of output percentage of output Cumulative maximum percentage defaulting purchasers output that PGE would be allocated. Operating Leases, Rent Expense Operating Leases, Rent Expense Long-term Contract for Purchase of Electric Power, Estimated Annual Cost Long-term Contract for Purchase of Electric Power, Estimated Annual Cost Future Minimum Sublease Rentals, Sale Leaseback Transactions, within One Year Future Minimum Sublease Rentals, Sale Leaseback Transactions, within One Year Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Five Years Operating Leases, Rent Expense, Sublease Rentals Operating Leases, Rent Expense, Sublease Rentals Ownership interest in Boardman sold Ownership interest in Boardman sold Ownership interest in Boardman sold in 1985. ownership interest in Pacific Northwest Intertie sold ownership interest in Pacific Northwest Intertie sold ownership interest in Pacific Northwest Intertie sold in 1985. maximum potential liability under power and transmission agreements maximum potential liability under power and transmission agreements maximum potential liability under power and transmission agreements related to Boardman in the next year. Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Four Years Schedule of Regulatory Assets and Liabilities [Text Block] Schedule of Regulatory Assets and Liabilities [Text Block] Regulatory Assets And Liabilities Regulatory Assets And Liabilities [Text Block] Regulatory Assets and Liabilities Disclosure Text Block Statement [Table] Statement, Scenario [Axis] Statement, Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Statement [Line Items] Statement [Line Items] Revenues, net Electric Revenue Operating expenses: Costs and Expenses [Abstract] Purchased power and fuel Cost of purchased power and fuel Costs of purchased power and fuel used to generate electricity. Production and distribution Electric Production Expense Administrative and other General and Administrative Expense Depreciation and amortization Depreciation, Depletion and Amortization Taxes other than income taxes Taxes, Miscellaneous Total operating expenses Costs and Expenses Income from operations Operating Income (Loss) Other income: Nonoperating Income (Expense) [Abstract] Miscellaneous income, net Other Nonoperating Income (Expense) Other income, net Nonoperating Income (Expense) Interest expense Interest Expense Income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Income taxes Income Tax Expense (Benefit) Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Less: net income (loss) attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Net income attributable to Portland General Electric Company Net Income (Loss) Attributable to Parent Weighted-average shares outstanding (in thousands): Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Earnings per share—basic and diluted Earnings Per Share, Basic and Diluted Dividends declared per common share Common Stock, Dividends, Per Share, Declared 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. Income Taxes Note [Abstract] Income Taxes Note [Abstract] Income Taxes Income Tax Disclosure [Text Block] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt, Type [Axis] Short-term Debt, Type [Axis] Short-term Debt, Type [Domain] Short-term Debt, Type [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Short-term Debt [Line Items] Short-term Debt [Line Items] Average daily amount of short-term debt outstanding Short-term Debt, Average Outstanding Amount Weighted daily average interest rate Short-term Debt, Weighted Average Interest Rate Maximum amount outstanding during the year Short-term Debt, Maximum amount outstanding during the year Short-term Debt, Maximum amount outstanding during the year Other current assets: Other current assets: [Abstract] Other current assets: [Abstract] Current deferred income tax asset Deferred Tax Assets, Net, Current Assets from price risk management activities Price risk management regulatory assets Price risk management regulatory assets Income taxes receivable Income Taxes Receivable, Current Other Other Assets, Miscellaneous Other Assets, Current Other Assets, Current Accrued expenses and other current liabilities: Accrued expenses and other current liabilities: [Abstract] Accrued expenses and other current liabilities: [Abstract] Accrued employee compensation and benefits Employee-related Liabilities, Current Accrued interest payable Interest Payable, Current Dividends payable Dividends Payable, Current Other Other Current Liabilities - Other Other Current Liabilities - Other Other Liabilities, Current Other Liabilities, Current Variable interest Entities [Abstract] Variable interest Entities [Abstract] Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Estimated Remaining Useful Life of Facility Acquired Estimated Remaining Useful Life of Facility Acquired Estimated useful life expected to be remaining at the date of purchase in a future period. Variable Interest Entity, Initial Consolidation, Gain (Loss) Variable Interest Entity, Initial Consolidation, Gain (Loss) Variable Interest Entity, Discount Rate Used in Impairment Calc Variable Interest Entity, Discount Rate Used in Impairment Calc Discount rate used in connection with impairment calculation for solar facilities owned by VIEs, which represents the reporting entity's allowed rate of return. Property, Plant and Equipment, Useful Life, Minimum Property, Plant and Equipment, Useful Life, Minimum Property, Plant and Equipment, Useful Life, Maximum Property, Plant and Equipment, Useful Life, Maximum Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Asset Retirement Obligation [Abstract] Asset Retirement Obligations Asset Retirement Obligation Disclosure [Text Block] Investments held in trust [Table] Investments held in trust [Table] Investments held in trust [Table] Nuclear Decommissioning [Member] Nuclear Decommissioning [Member] Nuclear Decommissioning Turst [Member] Cash equivalents Cash Equivalents, at Carrying Value Marketable securities, at fair value: Marketable Securities [Abstract] Equity securities Marketable Securities, Equity Securities Debt securities Available-for-sale Securities, Debt Securities Decommissioning Fund Investments, Fair Value Decommissioning Fund Investments, Fair Value Assets Held-in-trust, Noncurrent Assets Held-in-trust, Noncurrent Trojan decommissioning activities Trojan decommissioning activities Asset retirement obligation related to Trojan decommissioning activities Utility plant Asset Retirement Obligation - Utility Plant Asset Retirement Obligation - Utility Plant Non-utility property Asset Retirement Obligation - Non-utility property Asset Retirement Obligation - Non-utility property Asset retirement obligations Asset Retirement Obligations, Noncurrent Balance Sheet Components Note [Abstract] Balance sheet components note. Balance Sheet Components Details of Certain Balance Sheet Accounts Disclosure [Text Block] Details of Certain Balance Sheet Accounts Other Postretirement Benefit Plans [Member] Amounts included in comprehensive income: Amounts included in comprehensive income: [Abstract] Amounts included in comprehensive income: [Abstract] Net actuarial loss (gain) 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 Benefit obligation: Defined Benefit Plan, Estimated Future Benefit Payments [Abstract] As of January 1 Defined Benefit Plan, Benefit Obligation Fair value of plan assets: Assets, Fair Value Disclosure [Abstract] Participants’ contributions Defined Benefit Plan, Contributions by Plan Participants Actuarial loss (gain) Defined Benefit Plan, Actuarial Net (Gains) Losses Benefit payments Defined Benefit Plan, Benefits Paid As of January 1 Defined Benefit Plan, Fair Value of Plan Assets Unfunded position as of December 31 Defined Benefit Plan, Plans with Benefit Obligations in Excess of Plan Assets, Aggregate Benefit Obligation Defined Benefit Plan, Accumulated Benefit Obligation Defined Benefit Plan, Accumulated Benefit Obligation Actual return on plan assets Defined Benefit Plan, Actual Return on Plan Assets Company contributions Defined Benefit Plan, Contributions by Employer Classification in consolidated balance sheet: Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract] Noncurrent asset Current liability Pension and Other Postretirement Defined Benefit Plans, Current Liabilities Noncurrent liability Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent Amortization of net actuarial loss Defined Benefit Plan, Amortization of Net Gains (Losses) Amortization of prior service cost Amortization of prior service cost included in comprehensive income The amount of the prior service cost or credit recognized in net periodic benefit cost relating to benefit changes attributable to plan participants' prior service pursuant to a plan amendment or a plan initiation, amortization of which is included in comprehensive income. 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. Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Amounts included in AOCL: Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Gain (Loss), before Tax [Abstract] Net actuarial loss Net actuarial loss Net actuarial loss from Defined Benefit Plans included in Accumulated Other Comprehensive Income. Prior service cost Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Assumptions used: Defined Benefit Plan, Assumptions Used in Calculations [Abstract] Discount rate used to calculate benefit obligation Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Defined Benefit Plan Discount rate - upper range Defined Benefit Plan Discount rate - upper range The interest rate used to adjust for the time value of money for the Defiend Benefit Plan Discount rate - upper range. 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 Long-term rate of return on plan assets Long-term rate of return on plan assets Long-term rate of return on plan assets 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] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Pension and Other Postretirement Plans, Pensions, Policy [Policy Text Block] Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block] Pension and Other Postretirement Plans, Nonpension Benefits, Policy [Policy Text Block] Non-qualified benefit [Policy Text Block] Non-qualified benefit [Policy Text Block] Non-qualified benefit plans [Policy Text Block] Commitments and Guarantees [Abstract] Commitments and Guarantees [Abstract] Long-term Purchase Commitment [Table] Long-term Purchase Commitment [Table] Long-term Purchase Commitment by Category of Item Purchased [Axis] Long-term Purchase Commitment by Category of Item Purchased [Axis] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment, Category of Item Purchased [Domain] Long-term Purchase Commitment [Line Items] Long-term Purchase Commitment [Line Items] Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] Unrecorded Unconditional Purchase Obligations Disclosure [Table Text Block] 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] 2012 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2013 Long-term Debt, Maturities, Repayments of Principal in Year Two 2014 Long-term Debt, Maturities, Repayments of Principal in Year Three 2015 Long-term Debt, Maturities, Repayments of Principal in Year Four 2016 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Total long-term debt Long-term Debt Basis of Presentation [Abstract] Basis of Presentation [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Employee Stock Purchase Plan Note [Abstract] Employee Stock Purchase Plan Note [Abstract] Stock Purchase Plan [Text Block] Stock Purchase Plan [Text Block] Stock Purchase Plan Text Block Commitments and Contingencies, Policy [Policy Text Block] Commitments and Contingencies, Policy [Policy Text Block] Summary of Significant Accounting Policies Note [Abstract] Summary of Significant Accounting Policies Note [Abstract] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Schedule of Long-term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Long-term Debt, Type [Axis] Long-term Debt, Type [Axis] Long-term Debt, Type [Domain] Long-term Debt, Type [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] First Mortgage Bonds, rates range from 3.46% to 9.31%, with a weighted average rate of 5.83% in 2011 and 5.85% in 2010, due at various dates through 2040 Long-term Debt - First Mortgage Bonds Long-term Debt - First Mortgage Bonds Pollution Control Revenue Bonds: Long-term Pollution Control Bond [Abstract] Port of Morrow, Oregon, 5% rate, due 2033 Long-term Debt, Pollution Control Revenue Bonds - Port of Morrow, Oregon Long-term Debt, Pollution Control Revenue Bonds - Port of Morrow, Oregon City of Forsyth, Montana, 5% rate, due 2033 Long-term Debt, Pollution Control Revenue Bonds - City of Forsyth, Montana Long-term Debt, Pollution Control Revenue Bonds - City of Forsyth, Montana Port of St. Helens, Oregon, 5.25% rate, due in 2014 Long-term Debt, Pollution Control Revenue Bonds - Port of St. Helens, Oregon Long-term Debt, Pollution Control Revenue Bonds - Port of St. Helens, Oregon Total Pollution Control Revenue Bonds Long-term Pollution Control Bond Pollution Control Revenue Bonds owned by PGE Pollution Control Revenue Bonds owned by PGE Pollution Control Revenue Bonds owned by PGE Unamortized debt discount Debt Instrument, Unamortized Discount Less: current portion of long-term debt Long-term Debt, Current Maturities Long-term debt, net of current portion Long-term Debt, Excluding Current Maturities NOTE 5: PRICE RISK MANAGEMENT [Abstract] NOTE 5: PRICE RISK MANAGEMENT [Abstract] Schedule of Future Expected Realized Gains or Losses [Axis] Schedule of Future Expected Realized Gains or Losses [Axis] Component of Other Expense, Nonoperating, Name [Domain] Component of Other Expense, Nonoperating, Name [Domain] Gain (Loss) on Derivatives [Member] Commodity Contracts, Electricity Net Unrealized Gain or Loss as of Balance Sheet Date Related to Derivative Instruments, Commodity Contracts, Electricity Net unrealized gain or loss recorded as of the balance sheet date related to commodity contracts for electricity, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. Commodity Contracts, Natural Gas Net Unrealized Gain or Loss as of Balance Sheet Date Related to Derivative Instruments, Commodity Contracts, Natural Gas Net unrealized gain or loss recorded as of the balance sheet date related to commodity contracts for natural gas, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. Net unrealized loss Net Unrealized Gain or Loss as of Balance Sheet Date Related to Derivative Instruments Net unrealized gain or loss related to commodity contracts recorded as of the balance sheet date, expected to be realized in the statement of income in a future period as a result of the settlement of the underlying derivative instrument. Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock [Member] Common Stock Including Additional Paid in Capital [Member] Additional Paid-in Capital [Member] Accumulated Other Comprehensive Income (Loss) [Member] Retained Earnings [Member] Noncontrolling Interest [Member] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Balance, shares Shares, Issued Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Issuance of common stock, net of issuance costs, shares Stock Issued During Period, Shares, New Issues Issuance of common stock, net of issuance costs, value Proceeds from Issuance of Common Stock Vesting of restricted and performance stock units, shares Vesting of Restricted and Performance Stock Units, Shares Vesting of Restricted and Performance Stock Units, Shares. Vesting of restricted and performance stock units, value Vesting of Restricted and Performance Stock Units, Value Vesting of Restricted and Performance Stock Units, Value. Vesting of restricted stock units, shares Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Vesting of restricted stock units, value Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Issuance of shares pursuant to employee stock purchase plan, shares Stock Issued During Period, Shares, Employee Stock Purchase Plans Issuance of shares pursuant to employee stock purchase plan, value Stock Issued During Period, Value, Employee Stock Purchase Plan Issuance of shares pursuant to dividend reinvestment and direct stock purchase plan, shares Shares Issued During Period, Dividend Reinvestment and Direct Stock Purchase Plan Shares Issued During Period, Dividend Reinvestment and Direct Stock Purchase Plan Noncontrolling interests' capital contributions, value Noncontrolling Interests' Capital Contributions Noncontrolling Interests' Capital Contributions. Stock-based compensation Stock Granted During Period, Value, Share-based Compensation, Net of Forfeitures Dividends declared Dividends, Common Stock Net income (loss) Net Income (Loss) Attributable to Parent Net income and Net income attributable to Portland General Electric Company Net income and Net income attributable to Portland General Electric Company The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest and the portion of consolidated profit or loss for the period, net of income taxes, which is attributable to the parent. + References Net income and Net income attributable to Portland General Electric Company Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Balance, shares Balance Schedule of Variable Interest Entities [Table Text Block] Schedule of Variable Interest Entities [Table Text Block] Concentration Risk [Table] Concentration Risk [Table] Concentration Risk by Benchmark [Axis] Concentration Risk Type [Domain] Concentration Risk [Line Items] Concentration Risk [Line Items] Assets from price risk management activities: Assets from price risk management activities: [Abstract] Assets from price risk management activities: [Abstract] Counterparty A Counterparty A Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Counterparty B Counterparty B Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Counterparty C Counterparty C Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Counterparty D Counterparty D Individually significant counterparty of total assets arising from dreivative instruments from price risk management activities. Counterparty E Counterparty E Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Counterparty F Counterparty F for PRM assets Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Counterparty G Counterparty G for PRM Assets Individually significant counterparty of total assets arising from derivative instruments from price risk management activities. Concentration of Risk, Derivative Instruments, Assets Concentration of Risk, Derivative Instruments, Assets Represents aggregate of individually significant counterparties of total assets arising from derivative instruments from price risk management activities. Counterparty E Counterparty E for PRM Liabs Individually significant counterparty of total liabilities arising from derivative instruments from price risk management activities. Counterparty H Counterparty H for PRM Liabs Individually significant counterparty of total liabilities arising from derivative instruments from price risk management activities. Counterparty I Counterparty I for PRM Liabs Individually significant counterparty of total liabilities arising from derivative instruments from price risk management activities. Concentration of Risk, Derivative Instruments, Liabilities Concentration of Risk, Derivative Instruments, Liabilities Represents aggregate of individually significant counterparties of total liabilities arising from derivative instruments from price risk management activities. Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Allowance for Doubtful Accounts Receivable, Current Allowance for Doubtful Accounts Receivable, Current Preliminary engineering costs preliminary engineering Preliminary engineering costs recorded on the balance sheet. Preliminary engineering costs expensed Preliminary engineering costs expensed Preliminary engineering costs expensed Production, excluding thermal: Production, excluding thermal: [Abstract] Production plant, excluding thermal: [Abstract] Hydro estimated average service life - hydro production plant estimated average service life - hydro production plant Wind estimated average service life - wind production plant estimated average service life - wind production plant Transmission estimated average service lives - transmission plant estimated average service lives - transmission plant Distribution estimated average service lives - distribution plant estimated average service lives - distribution plant General estimated average service lives - general plant estimated average service lives - general plant Balance as of beginning of year Asset Retirement Obligation Liabilities incurred Asset Retirement Obligation, Liabilities Incurred Liabilities settled Asset Retirement Obligation, Liabilities Settled Accretion expense Asset Retirement Obligation, Accretion Expense Revisions in estimated cash flows Asset Retirement Obligation, Revision of Estimate Balance as of end of year Asset Retirement Obligations [Abstract] Asset Retirement Obligations [Abstract] Damages sought in USDOE claim Damages sought in USDOE claim Damages sought in USDOE claim PGE Share of Recovery from USDOE Claims PGE Share of Recovery from USDOE Claims PGE Share of Recovery from USDOE Claims Asset Retirement Obligation Increase related to Boardman plant Asset Retirement Obligation Increase related to Boardman plant Asset Retirement Obligation Increase related to Boardman plant due to updated decommissioning study. Asset Retirement Obligation Rate Recovery related to Trojan Plant Asset Retirement Obligation Rate Recovery related to Trojan Plant Asset Retirement Obligation Rate Recovery related to Trojan Plant Pension Contributions Pension Contributions Contribution to health reimbursement account - sick time contribution to health reimbursement account - sick time Contributions to the HRAs provide for claims by retirees for qualified medical costs. For active bargaining employees, the participants’ accounts are credited with 58% of the value of the employee’s accumulated sick time as of April 30, 2004. Contribution to health reimbursement account - earned time off contribution to health reimbursement account - earned time off Contributions to the HRAs provide for claims by retirees for qualified medical costs. For active bargaining employees, the participants’ accounts are credited with 100% of their earned time off accumulated at the time of retirement. Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year Net actuarial loss portion of amortization from AOCL for pension benefits net actuarial loss portion of amortization from AOCL for pension benefits The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented related to the net actuarial loss for pension benefits. Net Actuarial Loss Portion of Amortization from AOCL for Non-qualified benefits Net Actuarial Loss Portion of Amortization from AOCL for Non-qualified benefits The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, consisting of the net actuarial loss for non-qualified benefits. Net actuarial loss portion of amortiztion of AOCL for other postretirement benefits Net actuarial loss portion of amortiztion of AOCL for other postretirement benefits The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, consisting of the net actuarial loss for other postretiremnt benefits. Prior service cost portion of amortization of AOCL for pension benefits Prior service cost portion of amortization of AOCL for pension benefits The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, consisting of the prior service cost for pension benefits. Prior service cost portion of amortization of AOCL for other postretirement benefits Prior service cost portion of amortization of AOCL for other postretirement benefits The aggregate amount in accumulated other comprehensive income expected to be recognized as a component of net periodic benefit cost over the fiscal year that follows the most recent annual statement of financial position presented, consisting of the prior service cost for other postretirement benefits. Defined benefit plan, current annual rate of health care cost increase Defined benefit plan, current annual rate of health care cost increase The assumed health care cost trend rate for the current year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status. Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate 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 Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation 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. 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. 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. 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. 401k Plan Company contributions 401k Plan Company contributions 401k Plan, Company contributions during the year. 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] 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] Current: Current Income Tax Expense (Benefit) [Abstract] Federal Current Federal Tax Expense (Benefit) State and local Current State and Local Tax Expense (Benefit) Current Income Tax Expense (Benefit) Current Income Tax Expense (Benefit) Deferred: Deferred: [Abstract] Deferred: [Abstract] Federal Deferred Federal Income Tax Expense (Benefit) State and local Deferred State and Local Income Tax Expense (Benefit) deferred income tax expense deferred income tax expense - footnote deferred income tax expense - footnote Investment tax credit adjustments Income Tax Credits and Adjustments Income tax expense Capital Additions [Member] Capital Additions [Member] Long-term Contract for Purchase of Electric Power [Domain] Long-term Contract for Purchase of Electric Power [Domain] Electric Transmission [Member] Electric Transmission [Member] Public Utility Districts [Member] Public Utility Districts [Member] Future Minimum payments to Public Utility Districts for purchase obligations [Member] Public Utilities, Inventory, Fuel [Member] Public Utilities, Inventory, Fuel [Member] Coal Supply Agreements [Member] Coal Supply Agreements [Member] Lease Agreements [Member] Lease Agreements [Member] Commitments [Member] Commitments [Member] Unrecorded Unconditional Purchase Obligation Unrecorded Unconditional Purchase Obligation Unrecorded Unconditional Purchase Obligation, Due within One Year Unrecorded Unconditional Purchase Obligation, Due within One Year Unrecorded Unconditional Purchase Obligation, Due within Two Years Unrecorded Unconditional Purchase Obligation, Due within Two Years Unrecorded Unconditional Purchase Obligation, Due within Three Years Unrecorded Unconditional Purchase Obligation, Due within Three Years Unrecorded Unconditional Purchase Obligation, Due within Four Years Unrecorded Unconditional Purchase Obligation, Due within Four Years Unrecorded Unconditional Purchase Obligation, Due within Five Years Unrecorded Unconditional Purchase Obligation, Due within Five Years Unrecorded Unconditional Purchase Obligation, Due after Five Years Unrecorded Unconditional Purchase Obligation, Due after Five Years Cash flows from operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] 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] Deferred income taxes Deferred Income Tax Expense (Benefit) Renewable adjustment clause deferrals Renewable adjustment clause deferrals The deferral under the Company's Renewable Adjustment Clause mechanism of the amounts recorded in net income related to the Company's renewable energy projects that are expected to be recovered, or refunded, in future periods. Regulatory deferral of settled derivative instruments Regulatory deferral of settled derivative instruments Regulatory deferral of settled derivative instruments Power cost deferrals, net of amortization Deferred Purchased Power Costs Increase (decrease) in net liabilities from price risk management activities Increase (Decrease) in Risk Management Assets and Liabilities Regulatory deferrals--price risk management activities Increase (Decrease) in Regulatory Assets and Liabilities Senate Bill 408 amortization Senate Bill 408 deferrals, net The deferral of amounts recorded in net income under Oregon tax law, SB 408, which is deferred to the balance sheet. Amounts expected to be recovered from (or refunded to) customers in future periods. Allowance for equity funds used during construction Decoupling mechanism deferrals, net of amortization Decoupling Mechanism Deferrals, Net The deferral 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 in future periods. Unrealized gains on non-qualified benefit plan trust assets Unrealized Gain (Loss) on Securities Other non-cash income and expenses, net Other Noncash Income (Expense) Changes in working capital: Increase (Decrease) in Operating Capital [Abstract] (Increase) decrease in receivables and unbilled revenues Increase (Decrease) in Receivables Decrease (increase) in margin deposits Increase (Decrease) in Margin Deposits Outstanding Income tax refund received Proceeds from Income Tax Refunds Increase in income taxes receivable Increase (Decrease) in Income Taxes Receivable Increase (decrease) in payables and accrued liabilities Increase (Decrease) in Accounts Payable Other working capital items, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Contribution to pension plan Contribution to voluntary employees’ benefit association trust Contribution to the voluntary employees’ beneficiary association trust The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its non-pension postretirement benefit plans. Distribution of Trojan refund liability Distribution of Trojan Refund Liability Distribution of Trojan Refund Liability Other, net Increase (Decrease) in Other Operating Assets Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities Cash flows from investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital expenditures Payments to Acquire Property, Plant, and Equipment Purchases of nuclear decommissioning trust securities Payments to Acquire Investments to be Held in Decommissioning Trust Fund Sales of nuclear decommissioning trust securities Proceeds from Sale, Maturity and Collection of Investments Distribution from nuclear decommissioning fund Proceeds from Decommissioning Trust Fund Assets Other, net Payments for (Proceeds from) Other Investing Activities Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities Cash flows from financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Proceeds from issuance of long-term debt Proceeds from Issuance of Long-term Debt Payments on long-term debt Repayments of Long-term Debt Proceeds from Issuance of Common Stock, net of issuance cost Issuances (maturities) of commercial paper, net Proceeds from Issuance of Commercial Paper Borrowings on short-term debt Proceeds from Short-term Debt Payments on short-term debt Repayments of Short-term Debt Borrowings on revolving lines of credit Proceeds from Lines of Credit Payments on revolving lines of credit Repayments of Lines of Credit Dividends paid Payments of Dividends Premium paid on repayment of long-term debt Premium paid on repayment of long-term debt Premium paid on repayment of long-term debt Debt issuance costs Payments of Debt Issuance Costs Noncontrolling interests’ capital (distributions) contributions Proceeds from Noncontrolling Interests Net cash (used in) provided by financing activities Net Cash Provided by (Used in) Financing Activities Change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of year Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of year Supplemental disclosures of cash flow information: Supplemental Cash Flow Information [Abstract] Cash paid for interest, net of amounts capitalized Interest Paid, Net Cash paid for income taxes Income Taxes Paid Non-cash investing and financing activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Accrued capital additions Capital Expenditures Incurred but Not yet Paid Accrued dividends payable Dividends Payable, Amount Preliminary engineering transferred to Construction work in progress from Other noncurrent assets Preliminary engineering transferred to construction work in progress Preliminary engineering costs transferred to construction work in progress during the period Consolidation, Policy [Policy Text Block] Consolidation, Policy [Policy Text Block] Variable Interest Entities Details [Table] Variable Interest Entities Details [Table] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Cash and cash equivalents Variable Interest Entity, Consolidated, Carrying Amount, Cash and Cash Equivalents The carrying amount of the consolidated variable interest entities' cash and cash equivalents included in the reporting entity's statement of financial position. Accounts receivable Variable Interest Entity, Consolidated, CarryingAmount, Accounts Receivable, Net The carrying amount of the consolidated variable interest entities' accounts receivable, net included in the reporting entity's consolidated statement of financial position. Electric utility plant, net Variable Interest Entity, Consolidated, Carrying Amount, Electric Utility Plant, Net The carrying amount of the variable interest entities' electric utility plant, net included in the reporting entity's consolidated statement of financial position. Employee Benefits Pension and Other Postretirement Benefits Disclosure [Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Current assets: Assets, Current [Abstract] Current Assets, Commodity Contracts: Current Assets, Commodity Contracts: [Abstract] Commodity contracts: [Abstract] Commodity Contract Asset, Current, 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. Commodity Contract Asset, Current, 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. 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. Noncurrent assets: Assets, Noncurrent [Abstract] Noncurrent Assets, Commodity Contracts: [Abstract] Noncurrent Assets, Commodity Contracts: [Abstract] 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. 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. Total noncurrent derivative assets Noncurrent Derivative Assets 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. Total derivative assets not designated as hedging instruments Price Risk Derivative Instruments Not Designated as Hedging Instruments Asset, at Fair Value 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. Current liabilities: Liabilities, Current [Abstract] Commodity Contract Liability, Current, 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. Commodity Contract Liability, Current, 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. 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. Liabilities, Noncurrent [Abstract] Liabilities, Noncurrent [Abstract] Commodity Contract Liability, Noncurrent, 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. Commodity Contract Liability, Noncurrent, 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. 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. Total derivative liabilities not designated as hedging instruments Price Risk Derivative Instruments Not Designated as Hedging Instruments Liability, at Fair Value 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. 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] Total Non-qualified benefit plan trust assets [Domain] Total Non-qualified benefit plan trust assets [Domain] Total Non-qualified benefit plan trust assets [Domain] Other non-qualified benefit plan [Member] other non-qualified benefit plan [Member] other non-qualified benefit plan [Member] 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] Non-qualified benefit plan trust Non-qualified benefit plan liabilities Other Postretirement Defined Benefit Plan, Liabilities, Noncurrent Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] Schedule of Earnings Per Share, Basic, by Common Class, Including Two Class Method [Table] 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] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Weighted Average Number of Shares Outstanding, Basic Weighted Average Number Diluted Shares Outstanding Adjustment Weighted Average Number Diluted Shares Outstanding Adjustment Weighted Average Number of Shares Outstanding, Diluted Earnings Per Share, Basic Earnings Per Share, Basic Earnings Per Share, Basic and Diluted Federal statutory tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate Federal tax credits Effective Income Tax Rate Reconciliation, Tax Credits, Other State and local taxes, net of federal tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes Flow through depreciation and cost basis differences Effective Income Tax Rate Reconciliation, Nondeductible Expense, Depreciation Investment tax credit amortization Effective Income Tax Rate Reconciliation, Tax Credits, Investment Other Effective Income Tax Rate Reconciliation, Other Adjustments Effective tax rate Effective Income Tax Rate, Continuing Operations Schedule of Regulatory Assets [Table] Schedule of Regulatory Assets [Table] Regulatory Assets, Current [Member] Regulatory Assets, Current [Member] Current Regulatory Assets Regulatory Liability [Axis] Regulatory Liability [Axis] Regulatory Liability [Domain] Regulatory Liability [Domain] Current Regulatory Liabilities [Member] Current Regulatory Liabilities [Member] Current Regulatory Liabilities Noncurrent Regulatory Liabilities [Member] Noncurrent Regulatory Liabilities [Member] Noncurrent Regulatory Liabilities Regulatory Assets [Line Items] Regulatory Assets [Line Items] Remaining Recovery Period of Regulatory Assets, Price Risk Management Remaining Recovery Period of Regulatory Assets, Price Risk Management For Which No Return on Investment is Provided Remaining recovery period of regulatory assets, Price Risk Management, for which no return on investment during recovery period is provided. Remaining Recovery Period of Regulatory Asset, Deferred Broker Settlements Remaining Recovery Period of Regulatory Asset, Deferred Broker Settlements, For Which No Return on Investment During Recovery Period is Provided Remaining Recovery Period of Regulatory Asset, Deferred Broker Settlements, For Which No Return on Investment During Recovery Period is Provided Remaining Recovery Period of Regulatory Asset, Debt Reacquisition Costs Remaining Recovery Period of Regulatory Asset, Debt Reacquisition Costs, For Which No Return on Investment During Recovery Period is Provided Remaining Recovery Period of Regulatory Asset, Debt Reacquisition Costs, For Which No Return on Investment During Recovery Period is Provided Price risk management Pension and other postretirement plans Defined Benefit Plan, Assets for Plan Benefits, Noncurrent Deferred income taxes Deferred broker settlements Deferred broker settlements Deferred broker settlements Renewable energy deferral Renewable energy deferral Renewable energy deferral Debt reacquisition costs Deferred Finance Costs, Net Other Other Deferred Costs, Net Total regulatory assets Regulatory Assets Asset retirement removal costs Asset retirement removal costs Asset retirement removal costs Asset retirement obligations Power Cost Adjustment Mechanism Power Cost Adjustment Mechanism Regulatory deferral related to the Power Cost Adjustment Mechanism Trojan ISFSI pollution control tax credits Trojan ISFSI pollution control tax credits Trojan ISFSI pollution control tax credits Other Other regulatory liabilities Other regulatory liabilities Total regulatory liabilities Regulatory Liabilities Income Tax Uncertainties, Policy [Policy Text Block] Income Tax Uncertainties, Policy [Policy Text Block] Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block] Trade and Other Accounts Receivable, Unbilled Receivables, Policy [Policy Text Block] Marketable Securities, Policy [Policy Text Block] Marketable Securities, Policy [Policy Text Block] Plant Retirement and Abandonment, Policy [Policy Text Block] Plant Retirement and Abandonment, Policy [Policy Text Block] depreciation lives [Policy Text Block] depreciation lives [Policy Text Block] depreciation lives [Policy Text Block] Inventory, Policy [Policy Text Block] Inventory, Policy [Policy Text Block] Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Off-Balance-Sheet Credit Exposure, Policy [Policy Text Block] Trade and Other Accounts Receivable, Policy [Policy Text Block] Trade and Other Accounts Receivable, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents, Policy [Policy Text Block] Derivatives, Policy [Policy Text Block] Derivatives, Policy [Policy Text Block] 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] Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block] Property, Plant and Equipment, Planned Major Maintenance Activities, Policy [Policy Text Block] Allowance for Funds Used During Construction, Policy [Policy Text Block] Allowance for Funds Used During Construction, Policy [Policy Text Block] Regulatory Depreciation and Amortization, Policy [Policy Text Block] Regulatory Depreciation and Amortization, Policy [Policy Text Block] Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Goodwill and Intangible Assets, Intangible Assets, Policy [Policy Text Block] Public Utilities, Policy [Policy Text Block] Public Utilities, Policy [Policy Text Block] 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] Revenue Recognition, Policy [Policy Text Block] Revenue Recognition, Policy [Policy Text Block] franchise tax [Policy Text Block] franchise tax [Policy Text Block] franchise tax [Policy Text Block] Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] Income Tax, Policy [Policy Text Block] 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] 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 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 Shares Paid for Tax Withholding for Share Based Compensation Shares Paid for Tax Withholding for Share Based Compensation 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, Total Fair Value Share-based Compensation Share-based Compensation Adjustments Related to Tax Withholding for Share-based Compensation Adjustments Related to Tax Withholding for Share-based Compensation Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized 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. Stock-based Compensation, Forfeiture Rate Stock-based Compensation, Forfeiture Rate Forfeiture rate used in determining the period stock-based compensation expense. Line of Credit Facility [Abstract] Revolving Credit Facilities Revolving Credit Facilities [Text Block] Revolving Credit Facilities [Text Block] 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. Commodity Contracts, 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. Contracts, 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. Deferred income tax assets: Deferred Tax Assets, Net [Abstract] Price risk management Deferred Tax Assets, Price risk management The tax effect as of the balance sheet date of the amount of estimated future tax deductions arising from net liabilities from price risk management activities. Employee benefits Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Benefits 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. Tax loss carryforwards Deferred Tax Assets, Operating Loss Carryforwards Total deferred income tax assets Deferred Tax Assets, Net Deferred income tax liabilities: Deferred Tax Liabilities [Abstract] Depreciation and amortization Deferred Tax Liabilities, Property, Plant and Equipment Regulatory assets Deferred Tax Liabilities, Regulatory Assets Price risk management Deferred Tax Liabilities, Derivatives Other Deferred Tax Liabilities, Other Total deferred income tax liabilities Deferred Tax Liabilities Deferred income tax liability, net Deferred Tax Assets (Liabilities), Net Classification of net deferred income taxes: Deferred Tax Assets (Liabilities), Net [Abstract] Current deferred income tax liability Deferred Tax Liabilities, Current Noncurrent deferred income tax liability Deferred Tax Liabilities, Noncurrent Other comprehensive income - Change in compensation retirement benefits liability and amortization, net of taxes of $1 in 2011 and 2010 Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized (Gain) Loss Arising During Period, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive loss attributable to the noncontrolling interests Comprehensive income attributable to Portland General Electric Company Comprehensive Income (Loss), Net of Tax, Attributable to Parent Long-term Contracts for Purchase of Electric Power [Table] Long-term Contracts for Purchase of Electric Power [Table] Priest Rapids and Wanapum [Member] Priest Rapids and Wanapum [Member] Priest Rapids and Wanapum [Member] Wells [Member] Wells [Member] Wells [Member] Portland Hydro [Member] Portland Hydro [Member] Portland Hydro [Member] Long-term Contract for Purchase of Electric Power [Line Items] Long-term Contract for Purchase of Electric Power [Line Items] Revenue Bonds issued by the Public Utility Districts Revenue Bonds issued by the Public Utility Districts Revenue Bonds issued by the Public Utility Districts PGE Share of Output PGE Share of Output PGE Share of Output from the individual Public Utility Districts PGE Share of Capacity PGE portion of Capacity PGE portion of Capacity from Public Utility Districts Long-term Contract for Purchase of Electric Power, Date of Contract Expiration Long-term Contract for Purchase of Electric Power, Date of Contract Expiration commitment costs commitment costs commitment costs of contracts with the Public Utility Districts 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] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Allocation of Plan Assets [Table Text Block] Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Defined Benefit Plans Disclosures [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Net Benefit Costs [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of Expected Benefit Payments [Table Text Block] Schedule of allocation of plan assets [Table] schedule of allocation of plan assets [Table] schedule of allocation of plan assets [Table] Actual [Member] Scenario, Actual [Member] Target [Member] target [Member] target [Member] Equity Securities Defined Benefit Plan, Equity Securities Debt Securities Defined Benefit Plan, Target Allocation Percentage of Assets, Debt Securities Insurance contracts insurance contracts Portion of Non-qualified benefit plans assets invested in insurance contracts. Total Defined Benefit Plan, Actual Plan Asset Allocations Lointly-owned plant [Abstract] Lointly-owned plant [Abstract] Jointly Owned Utility Plant Interests [Table] Jointly Owned Utility Plant Interests [Table] Jointly Owned Utility Plant [Axis] Jointly Owned Utility Plant [Domain] Jointly Owned Utility Plant Interests [Line Items] Jointly Owned Utility Plant Interests [Line Items] Jointly Owned Utility Plant, Proportionate Ownership Share of Boardman Jointly Owned Utility Plant, Proportionate Ownership Share of Boardman The proportionate share of the reporting entity's interest (percent) in Boardman, a jointly owned utility plant. Jointly Owned Plant, Boardman Plant In Service Year Jointly Owned Plant, Boardman Plant In Service Year Plant in service year for Boardman, a jointly owned plant by the reporting entity. Jointly Owned Utility Plant, Gross Ownership Amount of Boardman Plant In Service Jointly Owned Utility Plant, Gross Ownership Amount of Boardman Plant In Service The period end amount owned by the reporting entity of a jointly owned utility (Boardman) plant in service. Jointly Owned Utility Plant, Ownership Amount of Boardman Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Boardman Plant Accumulated Depreciation The period end amount owned by the reporting entity of a jointly owned electricity generating facility (Boardman) plant accumulated depreciation. Jointly Owned Utility Plant Ownership Amount of Construction Work In Progress Boardman Jointly Owned Utility Plant Ownership Amount of Construction Work In Progress Boardman The reporting entity's period end amount of construction work in progress at Boardman, a jointly owned electricity generation plant. Jointly Owned Utility Plant, Proportionate Ownership Share of Colstrip Jointly Owned Utility Plant, Proportionate Ownership Share of Colstrip The proportionate share of the reporting entity's interest (percent) in Colstrip, a jointly owned utility plant. Jointly Owned Plant, Colstrip Plant In Service Year Jointly Owned Plant, Colstrip Plant In Service Year The plant in service year of Colstrip, a jointly owned plant by the reporting entity. Jointly Owned Utility Plant, Gross Ownership Amount of Colstrip Plant In Service Jointly Owned Utility Plant, Gross Ownership Amount of Colstrip Plant In Service The period end amount owned by the reporting entity of a jointly owned utility (Colstrip) plant in service. Jointly Owned Utility Plant, Ownership Amount of Colstrip Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Colstrip Plant Accumulated Depreciation The period end amount owned by the reporting entity of a jointly owned electricity generating facility (Colstrip) plant accumulated depreciation. Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress Colstrip Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress Colstrip The reporting entity's period end amount of construction work in progress at Colstrip, a jointly owned electricity generation plant. Jointly Owned Utility Plant, Proportionate Ownership Share of Pelton/Round Butte Jointly Owned Utility Plant, Proportionate Ownership Share of Pelton/Round Butte The reporting entity's interest (percent) in Pelton/Round/Butte, a jointly owned utility plant. Jointly Owned Plant, Pelton Plant in Service Year Jointly Owned Plant, Pelton in Service Year The plant in service year for Pelton, a jointly owned plant by the reporting entity. Jointly Owned Plant, Round Butte in Service Year Jointly Owned Plant, Round Butte in Service Year The plant in service year for Round Butte, a jointly owned plant by the reporting entity. Jointly Owned Utility Plant, Gross Ownership Amount of Pelton/Round Butte Plant In Service Jointly Owned Utility Plant, Gross Ownership Amount of Pelton/Round Butte Plant In Service The period end amount owned by the reporting entity of utility plant (Pelton/Round Butte) plant in service. Jointly Owned Utility Plant, Ownership Amount of Pelton/Round Butte Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Pelton/Round Butte Plant Accumulated Depreciation The period end amount owned by the reporting entity of a jointly owned electricity generating facility (Pelton/Round Butte) plant accumulated depreciation. Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress Pelton/Round Butte Jointly Owned Utility Plant Ownership Amount Of Construction Work In Progress Pelton/Round Butte The reporting entity's period end amount of construction work in progress at Pelton/Round Butte, a jointly owned electricity generation plant. Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service Jointly Owned Utility Plant, Gross Ownership Amount of Plant in Service Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Plant Accumulated Depreciation Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress Jointly Owned Utility Plant, Ownership Amount of Construction Work in Progress Price Risk Management Note [Abstract] Price risk management note. Price Risk Management Derivative Instruments and Hedging Activities Disclosure [Text Block] Commitments and Guarantees Note [Abstract] Commitments and Guarantees Note [Abstract] Commitments and Guarantees [Text Block] Commitments and Guarantees [Text Block] Commitments and Guarantees Text Block Share-based Compensation [Abstract] Stock-based Compensation Expense Disclosure of Share-based Compensation Arrangements by Share-based Payment Award [Table Text Block] Transfers in and out of Level 3 [Policy Text Block] Transfers in and out of Level 3 [Policy Text Block] Transfers in and out of Level 3 of the Fair Value Hierarchy [Policy Text Block] 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] Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments, Policy [Policy Text Block] Debt, Policy [Policy Text Block] Debt, Policy [Policy Text Block] NOTE 10: EMPLOYEE BENEFITS [Abstract] NOTE 10: EMPLOYEE BENEFITS [Abstract] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Fair Value of assets held by the pension plan classified as Level 3 [Axis] Fair Value of assets held by the pension plan classified as Level 3 [Axis] Fair Value of assets held by the pension plan classified as Level 3 [Axis] Private Equity Funds [Member] Private Equity Funds [Member] alternative assets [Member] alternative assets [Member] alternative assets [Member] Defined Benefit Plan, Fair Value of Plan Assets Purchases purchases of investments in pension plan assets purchases of investments in pension plan assets Sales Sales of investments in pension plan assets Sales of investments in pension plan assets Realized loss on sales Available-for-sale Securities, Gross Realized Gain (Loss) Purchases and sales, net Defined benefit plan, purchases and sales, net Defined benefit plan, purchases and sales, net Realized gain on sales Available-for-sale Securities, Gross Realized Gains Unrealized gain on assets Unrealized Gain (Loss) on Investments Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, by Balance Sheet Grouping, Disclosure Item Amounts [Axis] Fair Value, Disclosure Item Amounts [Domain] Fair Value, Disclosure Item Amounts [Domain] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Long-term Debt, Fair Value Long-term Debt, Fair Value Long-term Debt Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value by Asset Class [Axis] Fair Value by Asset Class [Axis] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, by Asset Class [Domain] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Net liabilities from price risk management activities as of beginning of year Net Liabilities From Price Risk Management Activities Classified As Level 3 Net Liabilities From Price Risk Management Activities Classified as Level 3 Net realized and unrealized losses Realized and Unrealized Gains and Losses, Net, Commodity Contract Realized and Unrealized Gains and Losses, Net, Commodity Contracts Purchases, issuances, and settlements, net Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases, Sales, Issuances, Settlements Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Purchases Settlements Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Net transfers out of Level 3 to Level 2 Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Transfers out of Level 3 Net liabilities from price risk management activities as of end of year 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. Derivatives, Fair Value, by Balance Sheet Location [Axis] Balance Sheet Location [Domain] Derivative, Collateral, Master Netting Arrangements, Letters of Credit Derivative, Collateral, Master Netting Arrangements, Letters of Credit The amount of collateral posted pursuant to derivative instruments with counterparties where a master netting arrangement exists, consisting of letters of credit. Derivative, Net Liability Position, Aggregate Fair Value Derivative, Net Liability Position, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value Collateral Already Posted, Aggregate Fair Value 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. Volume Related to Derivative Instruments Held at Balance Sheet Date, Foreign Currency Volume Related to Derivative Instruments Held at Balance Sheet Date, Foreign Currency 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 foreign currency. Jointly-owned Plant [Abstract] Jointly-owned Plant [Abstract] Schedule of Jointly Owned Utility Plants [Table Text Block] Schedule of Jointly Owned Utility Plants [Table Text Block] Balance Sheet Compnents [Abstract] Balance Sheet Compnents [Abstract] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Accounts, Notes, Loans and Financing Receivable [Line Items] Balance as of beginning of year Increase in provision Provision for Doubtful Accounts Amounts written off, less recoveries Amounts written off, less recoveries Amounts written off, less recoveries Balance as of end of year Preliminary Engineering [Policy Text Block] Preliminary Engineering [Policy Text Block] Preliminary Engineering [Policy Text Block] Schedule of Regulatory Assets and Liabilities [Table Text Block] Schedule of Regulatory Assets and Liabilities [Table Text Block] Tabular disclosure of assets and liabilities that are created in connection with regulatory accounting [Table Text Block] Schedule of Price Risk Derivatives [Table Text Block] Schedule of Price Risk Derivatives [Table Text Block] 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] Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Other Derivatives Not Designated as Hedging Instruments, Statements of Financial Performance and Financial Position, Location [Table Text Block] Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Schedule of Concentration of Risk, by Counterparty [Table Text Block] Schedule of Concentration of Risk, by Counterparty [Table Text Block] Tabular disclosure of counterparties representing 10% or more of assets and liabilities from price risk management activities recorded in the reporting entity's statement of financial position. Incorporated Cities Incorporated Cities Number of incorporated cities in service area. Service Area Sq Miles Service Area Sq Miles Approximate square miles of service area. Number of Retail Customers Number of Retail Customers Includes residential, commercial and industrial. Service area population Service Area Population Service Area Population Percent of State's Population Percent of State's Population Service area population as a percent of the state's population. Entity Number of Employees Entity Number of Employees Number of Union Employees Number of Union Employees Number of employees subject to collective bargaining agreements. Number of Union Employees Subject to Agreement A Number of Union Employees Subject to Agreement A Number of employees subject to collective bargaining agreement A. 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. Other Accrued Liabilities, Current Other Accrued Liabilities, Current Dividend Reinvestment and Direct Stock Purchase Plan [Abstract] Dividend Reinvestment and Direct Stock Purchase Plan [Abstract] 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 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 Employee stock purchase plans [Abstract] Employee stock purchase plans [Abstract] employee stock purchase plan shares authorized employee stock purchase plan shares authorized employee stock purchase plan shares authorized Employee Stock Purchase Plan, Base Pay Threshold Employee Stock Purchase Plan, Base Pay Threshold Employee Stock Purchase Plan, Base Pay Threshold Employee Stock Purchase Plan, Purchased Stock Value Limitation Employee Stock Purchase Plan, Purchased Stock Value Limitation Employee Stock Purchase Plan, Purchased Stock Value Limitation Employee Stock Purchase Plan, Share Purchase Limitation Employee Stock Purchase Plan, Share Purchase Limitation Employee Stock Purchase Plan, Share Purchase Limitation 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. Employee Stock Purchase Plan, Number of Available Shares Employee Stock Purchase Plan, Number of Available Shares Employee Stock Purchase Plan, Number of Available Shares Domestic Domestic equity securities - defined benefit pension plan assets Domestic equity securities - defined benefit pension plan assets Debt securities—Domestic government Debt securities—Domestic government Other Postretirement Benefit Plan assets Debt securities—Domestic government Other Postretirement Benefit Plan assets Defined Benefit Pension Plan assets: Defined Benefit Plan, Funded Status of Plan [Abstract] Equity securities: Equity securities: [Abstract] Equity securities: [Abstract] Domestic Domestic equity securities - Other postretirement benefit plan assets at fair value Domestic equity securities - Other postretirement benefit plan assets at fair value Domestic International International International equity securities - other post retirement assets at fair value International equity securities - other post retirement assets at fair value Debt securities: Debt securities: [Abstract] Debt securities: [Abstract] Domestic government and corporate credit Domestic government and corporate credit defined benefit pension plan assets Domestic government and corporate credit defined benefit pension plan assets Domestic government and corporate credit Corporate credit Private equity funds Private equity funds Private equity fund securities held in Defined Benefit Pension Plan assets Alternative investments Alternative Investments, Fair Value Disclosure Defined Benefit Plan, Fair Value of Plan Assets Other Postretirement Benefit Plans assets: Other Postretirement Benefit Plans assets: [Abstract] Other Postretirement Benefit Plans assets: [Abstract] Money market funds Money market funds - other post retirement benefit plan assets at fair value Money market funds - other post retirement benefit plan assets at fair value Debt securities—Domestic government Other post retirement benefit plan assets total other post retirement benefit plan assets total other post retirement benefit plan assets total Money market funds Money market funds - defined benefit pension plan assets Money market funds - defined benefit pension plan assets International International equity securities - defined benefit pension plan assets International equity securities - defined benefit pension plan assets Minimum Guarantees, Policy [Policy Text Block] Minimum Guarantees, Policy [Policy Text Block] ASSETS Assets [Abstract] Cash and cash equivalents Accounts receivable, net Accounts Receivable, Net, Current Unbilled revenues Unbilled Revenue Carrying amount at the balance sheet date of revenues which have been earned but not yet billed. Inventories, at average cost: Energy Related Inventory [Abstract] Materials and supplies Other Inventory, Supplies Fuel Energy Related Inventory Regulatory assets--current Regulatory Assets, Current Other current assets Total current assets Assets, Current Electric utility plant: Public Utilities, Property, Plant and Equipment, Net [Abstract] Production Public Utilities, Property, Plant and Equipment, Generation or Processing Transmission Public Utilities, Property, Plant and Equipment, Transmission Distribution Public Utilities, Property, Plant and Equipment, Distribution General Public Utilities, Property, Plant and Equipment, General Public Utilities, Property, Plant and Equipment, General Intangible Public Utilities, Property, Plant and Equipment, Intangible Public Utilities, Property, Plant and Equipment, Intangible Construction work in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Total electric utility plant Public Utilities, Property, Plant and Equipment, Plant in Service Accumulated depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Electric utility plant, net Public Utilities, Property, Plant and Equipment, Net Regulatory assets--noncurrent Regulatory Assets, Noncurrent Nuclear decommissioning trust Other noncurrent assets Other Assets, Noncurrent Total assets Assets Liabilities and Equity [Abstract] Accounts payable Accounts Payable and Accrued Liabilities, Current Liabilities from price risk management activities-current Derivative Liabilities, Current Short-term debt Current portion of long-term debt Regulatory liabilities--current Regulatory Liability, Current Accrued expenses and other current liabilities Total current liabilities Liabilities, Current Regulatory liabilities--noncurrent Regulatory Liability, Noncurrent Deferred income taxes Liabilities from price risk management activities--noncurrent Derivative Liabilities, Noncurrent Unfunded status of pension and postretirement plans Other noncurrent liabilities Other Liabilities, Noncurrent Total liabilities Liabilities Commitments and Contingencies Commitments and Contingencies Equity: Equity [Abstract] Portland General Electric Company shareholders’ equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, no par value, 30,000,000 shares authorized; none issued and outstanding Preferred Stock, Value, Issued Common stock, no par value, 160,000,000 shares authorized; 75,362,956 and 75,316,419 shares issued and outstanding as of December 31, 2011 and 2010, respectively Common Stock, Value, Issued Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Retained earnings Retained Earnings (Accumulated Deficit) Total Portland General Electric Company shareholders’ equity Stockholders' Equity Attributable to Parent Noncontrolling interests' equity Stockholders' Equity Attributable to Noncontrolling Interest Total equity Total liabilities and equity Liabilities and Equity Debt Instrument, Decrease, Repayments Debt Instrument, Decrease, Repayments Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage City of Forsyth Bond rate City of Forsyth Bond rate City of Forsyth Bond rate First Mortgage Bonds - maximum rate First Mortgage Bonds - maximum rate First Mortgage Bonds - maximum rate First mortgage Bonds - minimum rate First mortgage Bonds - minimum rate First mortgage Bonds - minimum rate Port of Morrow Bond Rate Port of Morrow Bond Rate Port of Morrow Bond Rate Port of St. Helens Bond rate Port of St. Helens Bond rate Port of St. Helens Bond rate Debt, Weighted Average Interest Rate Debt, Weighted Average Interest Rate Contingencies Note [Abstract] Contingencies note. Contingencies [Text Block] Contingencies [Text Block] Includes disclosure of contingencies. This element may be used as a single block of text to encapsulate the entire disclosure including data and tables. Consolidated Statement of Comprehensive Income Parentheticals [Abstract] Consolidated Statement of Comprehensive Income Parentheticals [Abstract] Net Taxes on change in compensation retirement benefits liability and amortization Net Taxes on change in compensation retirement benefits liability and amortization Net Taxes on change in compensation retirement benefits liability and amortization Taxes on Pension and other postretirement plans' funded position Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax Taxes on reclassification of defined benefit pension plan and other benefits to regulatory (asset) liability Taxes on reclassification of defined benefit pension plan and other benefits to regulatory (asset) liability Taxes on reclassification of defined benefit pension plan and other benefits to regulatory (asset) liability Taxes on reclassification to net income for contract settlements Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Tax Taxes on reclassification of net realized and unrealized gains to regulatory liabilities Taxes on reclassification of net realized and unrealized gains to regulatory liabilities Taxes on reclassification of net realized and unrealized gains to regulatory liabilities Consolidated Statements of Equity (Parentheticals) [Abstract] Consolidated Statements of Equity (Parentheticals) [Abstract] Statement, Equity Components [Axis] Parent [Member] Parent [Member] Common Stock [Member] Preferred Stock [Member] Preferred Stock [Member] Capital Units [Member] Capital Units [Member] Common Stock Including Additional Paid in Capital [Member] Preferred Stock Including Additional Paid in Capital [Member] Preferred Stock Including Additional Paid in Capital [Member] Additional Paid-in Capital [Member] Other Additional Capital [Member] Other Additional Capital [Member] Deferred Compensation, Share-based Payments [Member] Deferred Compensation, Share-based Payments [Member] Treasury Stock [Member] Treasury Stock [Member] Retained Earnings [Member] Retained Earnings, Appropriated [Member] Retained Earnings, Appropriated [Member] Retained Earnings, Unappropriated [Member] Retained Earnings, Unappropriated [Member] Undistributed Income from Other than Gain or Loss on Sale of Properties [Member] Undistributed Income from Other than Gain (Loss) on Sale of Properties [Member] Undistributed Net Realized Gain or Loss on Sale of Properties [Member] Undistributed Net Realized Gain (Loss) on Sale of Properties [Member] Accumulated Distributions in Excess of Net Income [Member] Accumulated Distributions in Excess of Net Income [Member] Accumulated Other Comprehensive Income [Member] Accumulated Net Unrealized Investment Gain (Loss) [Member] Accumulated Net Unrealized Investment Gain (Loss) [Member] Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] Accumulated Translation Adjustment [Member] Accumulated Translation Adjustment [Member] Accumulated Defined Benefit Plans Adjustment [Member] Accumulated Defined Benefit Plans Adjustment [Member] Noncontrolling Interest [Member] Comprehensive Income [Member] Comprehensive Income [Member] Issuance costs Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Consolidated Balance Sheets Parentheticals [Abstract] Consolidated Balance Sheets Parentheticals [Abstract] Stockholders' equity: Preferred stock, no par value Preferred Stock, No Par Value Preferred stock, shares authorized Preferred Stock, Shares Authorized Preferred stock, issued Preferred Stock, Shares Issued Preferred stock, outstanding Preferred Stock, Shares Outstanding Common stock, no par value Common Stock, No Par Value Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Document and Entity Information [Abstract] Document and Entity Information [Abstract] Document Information [Table] Document Information [Table] Document Information, Document [Axis] Document Information, Document [Axis] Document [Domain] Document [Domain] Document Information [Line Items] Document Information [Line Items] EntityRegistrantName Entity Registrant Name EntityCentralIndexKey Entity Central Index Key DocumentType Document Type DocumentPeriodEndDate Document Period End Date AmendmentFlag Amendment Flag DocumentFiscalYearFocus Document Fiscal Year Focus DocumentFiscalPeriodFocus Document Fiscal Period Focus CurrentFiscalYearEndDate Current Fiscal Year End Date EntityWellKnownSeasonedIssuer Entity Well-known Seasoned Issuer EntityCurrentReportingStatus Entity Current Reporting Status EntityVoluntaryFilers Entity Voluntary Filers EntityFilerCategory Entity Filer Category EntityCommonStockSharesOutstanding Entity Common Stock, Shares Outstanding EntityPublicFloat Entity Public Float TradingSymbol Trading Symbol