Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Smokehouse remaining probable loss Smokehouse remaining probable loss Smokehouse remaining probable loss Less accumulated depreciation Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Document Fiscal Year Focus Document Fiscal Year Focus Number of unsubmitted claims settled related to the Smokehouse Creek Fire Complex Number of unsubmitted claims settled related to the Smokehouse Creek Fire Complex Number of unsubmitted claims settled related to the Smokehouse Creek Fire Complex Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Alternative and Other Alternative and Other [Member] Alternative and Other [Member] Customer [Axis] Customer [Axis] Segment Reporting [Abstract] Common stock — 200 shares authorized of $1.00 par value; 100 shares outstanding at June 30, 2026 and Dec. 31, 2025, respectively Common Stock, Value, Issued Depreciation and amortization Depreciation, Amortization and Accretion, Net Interest charges and other financing costs Interest Expense, Operating and Nonoperating Public Utilities, General Disclosures [Line Items] Public Utilities, General Disclosures [Line Items] State income taxes, net of federal tax effect (c) Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Benefit Plans and Other Postretirement Benefits Retirement Benefits [Text Block] Restatement Determination Date Restatement Determination Date Return Cash Collateral Derivative Asset, Subject to Master Netting Arrangement, Collateral, Obligation to Return Cash, Offset Against Derivative Asset Expected return on plan assets (a) Defined Benefit Plan, Expected Return (Loss) on Plan Assets Derivative Instrument [Axis] Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Measurement Frequency [Axis] Measurement Frequency [Axis] Property, Plant and Equipment, Net Public Utility Property, Plant, and Equipment [Table Text Block] Industry of Counterparty, Type [Axis] Industry of Counterparty, Type [Axis] Regulatory liabilities Regulatory Liability, Noncurrent Amendment Flag Amendment Flag Consolidated Entities [Axis] Consolidated Entities [Axis] Current liabilities Liabilities, Current [Abstract] Series Due Aug. 15, 2047 Series Due Aug. 15, 2047 [Member] Series Due Aug. 15, 2047 Gross Notional Amounts of Commodity FTRs Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Inventory [Axis] Inventory [Axis] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Allowance for funds used during construction — equity Allowance for equity funds used during construction Public Utilities, Allowance for Funds Used During Construction, Capitalized Cost of Equity Smokehouse probable loss Smokehouse probable loss Smokehouse probable loss Retail Retail Distribution [Member] Retail Distribution [Member] Consolidated Entities [Domain] Consolidated Entities [Domain] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Entity Address, State or Province Entity Address, State or Province Settlements Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Settlements PEO Total Compensation Amount PEO Total Compensation Amount Common Stock, Par or Stated Value Per Share Common Stock, Par or Stated Value Per Share Inventories Schedule of Utility Inventory [Table Text Block] Retirement Benefits [Abstract] Retirement Benefits [Abstract] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] Commodity contracts designated as cash flow hedges Commodity contracts designated as cash flow hedges Commodity contracts designated as cash flow hedges Regulatory assets Regulatory Asset, Noncurrent Total current liabilities Liabilities, Current Taxes (other than income taxes) Taxes, Miscellaneous Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Entity Address, City or Town Entity Address, City or Town Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Credit exposure Wholesale, trading and non trading commodity credit exposure for the most significant counterparties Wholesale, trading and non-trading commodity credit exposure for the entity's most significant counterparties. Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Credit exposure, percentage Percentage of wholesale, trading and non trading commodity credit exposure for the most significant counterparties Percentage of wholesale, trading and non-trading commodity credit exposure for the entity's most significant counterparties. Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Mwh of electricity Derivative, Nonmonetary Notional Amount Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Borrowing limit Line of Credit Facility, Maximum Borrowing Capacity Credit Facility Line of Credit Facility, Maximum Borrowing Capacity Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Xcel Energy Inc. Parent Company [Member] PTCs (a) Effective Income Tax Rate Reconciliation, Tax Credit, Percent Concentration Risk Type [Axis] Concentration Risk Type [Axis] Contributions of capital by parent Adjustments to Additional Paid in Capital, Other Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Accrued property, plant and equipment additions Capital Expenditures Incurred but Not yet Paid Segment Reporting Segment Reporting [Table Text Block] Deferred credits and other liabilities Liabilities, Other than Long-Term Debt, Noncurrent [Abstract] Insurance coverage remaining Insurance coverage remaining Insurance coverage remaining Related Party, Type [Axis] Related and Nonrelated Parties [Axis] Series Due Nov. 15, 2048 Series Due Nov. 15, 2048 [Member] Series Due Nov. 15, 2048 Long-term Debt, Carrying Amount Long-Term Debt Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Document Period End Date Document Period End Date Changes in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Debt Instrument, Face Amount Debt Instrument, Face Amount Operating expenses Costs and Expenses [Abstract] Electric plant Public Utilities, Property, Plant and Equipment, Generation or Processing Series due August 15, 2056 Series due August 15, 2056 [Member] Series due August 15, 2056 Lessee, Lease, Description [Line Items] Lessee, Lease, Description [Line Items] Electric fuel and purchased power Electric Fuel and Purchased Power Electric Fuel and Purchased Power Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Generating capacity (in MW) Generating capacity under long term purchased power agreements Generating capacity under long-term purchased power agreements. Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Contributions to pension plans Payment for Pension Benefits Operating lease liabilities Operating Lease, Liability, Current Operating Lease, Liability, Current Accrued interest Interest Payable, Current Name Outstanding Recovery, Individual Name Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation Defined Benefit Plan Credits Not Recognized Due To Effects of Regulation The additional amount of credits not recognized in net periodic benefit as reported in the financial statements of the entity due to effects of regulation. Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Net periodic benefit cost (credit) Defined Benefit Plan Net Benefit Cost (Credit) Recognized Before Regulatory Adjustments The total mount of net periodic benefit cost, before regulatory adjustments, for defined benefit plans for the period. Periodic benefit costs include the following components: service cost, interest cost, expected return on plan assets, gain or loss, prior service cost or credit, transition asset or obligation, and gain or loss due to settlements or curtailments, before regulatory adjustments. Depreciation and amortization Utilities Operating Expense, Depreciation and Amortization Utilities Operating Expense, Depreciation and Amortization Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Company Selected Measure Name Company Selected Measure Name Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Electric Commodity [Member] Electric Commodity [Member] Derivative instrument whose primary underlying risk is tied to electric commodity prices. Other MGP, Landfill, or Disposal Sites Other MGP, Landfill, or Disposal Sites [Member] Credit Facility [Domain] Credit Facility [Domain] Operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Compensation Amount Outstanding Recovery Compensation Amount Dividends payable to parent Dividends Payable, Current Individual: Individual [Axis] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Pension and employee benefit obligations Liability, Defined Benefit Plan, Noncurrent Line of Credit Facility [Table] Line of Credit Facility [Table] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Accrued unbilled revenues Accrued Unbilled Revenues The amount of fees and other revenue, excluding investment income receivable, earned but not yet received, which were recognized in conformity with revenue recognition criteria based on estimates or specific contractual terms. Commercial Paper Commercial Paper [Member] Smokehouse settlements reached Smokehouse settlements reached Smokehouse settlements reached Lessee, Operating Lease, Liability, Undiscounted Excess Amount Lessee, Operating Lease, Liability, Undiscounted Excess Amount Derivative instruments designated as fair value hedges Fair Value Hedges, Net Regulated Operating Revenue, Electric Regulated Operating Revenue, Electric Regulated Operating Revenue, Electric Short-term debt Short-Term Debt Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Award Timing Predetermined Award Timing Predetermined [Flag] Property, plant and equipment, net Public Utilities, Property, Plant and Equipment, Net Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Level 1 Fair Value, Inputs, Level 1 [Member] PTCs (a) Effective Income Tax Rate Reconciliation, Tax Credit, Amount Effective income tax rate Effective Income Tax Rate Reconciliation, Percent Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Lessee, Operating Lease, Liability, to be Paid Lessee, Operating Lease, Liability, to be Paid Allowance for funds used during construction — debt Public Utilities, Allowance For Funds Used During Construction, Capitalized Cost Of Debt The component of the allowance for funds used during construction during the period based on an assumed rate of return on debt capital used in financing the construction of regulated assets. Regulated Electric Segment Regulated Electric Segment [Member] Regulated Electric Segment All Executive Categories All Executive Categories [Member] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Long-term Debt, Fair Value Long-Term Debt, Fair Value Components of Net Periodic Benefit Cost (Credit) Schedule of Net Benefit Costs [Table Text Block] Total interest charges and financing costs Interest and Debt Expense Interest and Debt Expense Pre-Tax fair value gains (losses) recognized during the period in Pre-Tax fair value gains (losses) recognized during the period in Pre-Tax fair value gains (losses) recognized during the period in Operating lease right-of-use assets Operating Lease, Right-of-Use Asset Legal Fees Legal Fees Concentration Risk Type [Domain] Concentration Risk Type [Domain] Demand side management expenses Conservation and Demand Side Management Program Expenses Costs incurred for energy conservation, weatherization and other programs to conserve or manage energy use by customers. Impact of Derivative Activity on Accumulated Other Comprehensive Loss, Regulatory Assets and Liabilities, and Income [Abstract] Impact of Derivative Activity on Accumulated Other Comprehensive Loss Regulatory Assets and Liabilities and Income [Abstract] -- None. No documentation exists for this element. -- Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Segment Reporting Segment Reporting [Text Block] Direct advances on the credit facility outstanding Long-Term Line of Credit Dividends paid to parent Payments of Ordinary Dividends, Common Stock Expiration Date Trading Arrangement Expiration Date Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Wholesale Wholesale Distribution [Member] Wholesale Distribution [Member] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation Number of identified MGP, landfill, or disposal sites under current investigation and/or remediation Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Internal investment grade Internal Investment Grade [Member] Nonrelated Party Nonrelated Party [Member] Affiliated Entity Affiliated Entity [Member] Dividends declared to parent Dividends, Common Stock Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Common Stock, Shares Authorized Common Stock, Shares Authorized Accounts receivable Increase (Decrease) in Accounts and Other Receivables Industry of Counterparty [Domain] Industry of Counterparty [Domain] Electric Commodity Electric Commodity Contract [Member] Derivative instrument whose primary underlying risk is tied to electric commodity prices. Exercise Price Award Exercise Price AFUDC equity Effective Income Tax Rate Reconciliation, AFUDC Equity, Amount Effective Income Tax Rate Reconciliation, AFUDC Equity, Amount Investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Fair Value, Recurring [Member] Fair Value, Recurring [Member] Segment Reporting [Line Items] Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] Interest Rate Swap [Member] Interest Rate Swap [Member] Borrowings and Other Financing Instruments Debt Disclosure [Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Equity Component [Domain] Equity Component [Domain] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Line of Credit Facility [Abstract] Line of Credit Facility [Abstract] Accounts receivable Accounts Receivable, before Allowance for Credit Loss, Current Total operating expenses Costs and Expenses Adoption Date Trading Arrangement Adoption Date Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Total common stockholder's equity Equity, Attributable to Parent Assets Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Significant counterparties Number of most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure Number of the entity's most significant counterparties for wholesale, trading and non-trading commodity activities with credit exposure. Accounting Policies [Abstract] Accounting Policies [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Environmental Remediation Site [Axis] Environmental Remediation Site [Axis] Operating Lease, Liability Operating Lease, Liability Insider Trading Policies and Procedures [Line Items] Accounts Receivable, Allowance for Credit Loss, Current Accounts Receivable, Allowance for Credit Loss, Current Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Prepayments and other Prepaid Expense and Other Assets, Current Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Deferred income taxes Deferred Income Tax Expense (Benefit) Selected Balance Sheet Data Supplemental Balance Sheet Disclosures [Text Block] Regulatory assets Regulatory Asset, Current Net gains recognized as regulatory assets and liabilities Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Net Losses Gains Recognized As Regulatory Assets And Liabilities This element represents total gains (losses) for the period (realized and unrealized), arising from net assets and liabilities measured at fair value on a recurring basis using unobservable inputs (Level 3), which are recognized in regulatory assets and liabilities. Letter of Credit Letter of Credit [Member] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Entity Central Index Key Entity Central Index Key Components of Net Periodic Benefit Cost (Credit) [Abstract] Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] Additional paid in capital Additional Paid in Capital, Common Stock All Adjustments to Compensation All Adjustments to Compensation [Member] Other, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Federal statutory rate impact Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Income Statement [Abstract] Income Statement [Abstract] Credit Quality Indicator [Domain] Credit Quality Indicator [Domain] Credit quality indicators related to credit exposure. Document Transition Report Document Transition Report Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Purchased Power Agreements [Abstract] Purchased Power Agreements [Abstract] -- None. No documentation exists for this element. -- Municipal or cooperative electric entities or other utilities Municipal or Cooperative Entities or Other Utilities [Member] Municipal or Cooperative Entities or Other Utilities [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] City Area Code City Area Code Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Allowance for equity funds used during construction Allowance for Funds Used During Construction, Investing Activities All Individuals All Individuals [Member] Number Of Reportable Segments, Disclosed By Definition, Flag Number Of Reportable Segments, Disclosed By Definition, Flag Number Of Reportable Segments, Disclosed By Definition, Flag SPP OATT Upgrade Costs SPP OATT Upgrade Costs SPP OATT Upgrade Costs cash flow hedge commodity cash flow hedge commodity [Member] cash flow hedge commodity [Member] Name Forgone Recovery, Individual Name Balance Sheet Related Disclosures [Abstract] Balance Sheet Related Disclosures [Abstract] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Statement [Line Items] Statement [Line Items] Total assets Assets Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Entity [Domain] Entity [Domain] New Accounting Pronouncements and Changes in Accounting Principles [Abstract] Accounting Standards Update and Change in Accounting Principle [Abstract] Total revenues Operating Segments [Member] PEO PEO [Member] SPS SPS [Member] SPS is an operating utility engaged primarily in the generation, purchase, transmission, distribution and sale of electricity in portions of Texas and New Mexico. Other Other Liabilities, Noncurrent Retirement Plan Type [Axis] Retirement Plan Type [Axis] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Retained Earnings Retained Earnings [Member] Operating lease liabilities Operating Lease, Liability, Noncurrent Taxes accrued Taxes Payable, Current Revolving Credit Facility [Member] Credit Facility Revolving Credit Facility [Member] Other Effective Income Tax Rate Reconciliation, Tax Credit, Other, Percent Transmission Transmission Services [Member] Transmission Services [Member] Inventory transfers to property, plant and equipment Inventory transfers to plant, property and equipment Amount of increase (decrease) of plant, property and equipment reclassified from inventory. Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Increase (Decrease) in Stockholders' Equity Increase (Decrease) in Stockholders' Equity [Roll Forward] Common Stock, Shares, Outstanding Beginning balance (in shares) Ending balance (in shares) Common Stock, Shares, Outstanding Award Timing Disclosures [Line Items] Carrying Amount and Fair Value of Long-term Debt Fair Value, by Balance Sheet Grouping [Table Text Block] Changes in Level 3 Commodity Derivatives Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] Entity Current Reporting Status Entity Current Reporting Status Net cash provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Pension and other employee benefit obligations Increase (Decrease) in Employee Related Liabilities Provision for bad debts Provision for Bad Debts Provision for Bad Debts Inventory [Domain] Inventory [Domain] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Adjustments to reconcile net income to cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Revenue from contracts with customers Revenue from Contract with Customer, Excluding Assessed Tax Property, plant and equipment, net Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization Financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Smokehouse settlements paid Smokehouse settlements paid Smokehouse settlements paid C&I Commercial and Industrial Customers [Member] Commercial and Industrial Customers [Member] Available Line of Credit Facility, Remaining Borrowing Capacity Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Interest cost (a) Defined Benefit Plan, Interest Cost Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Underlying Securities Award Underlying Securities Amount Revenue Revenue from Contract with Customer [Text Block] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] PPAs Purchased Power Agreements [Member] Purchased Power Agreements [Member] Other current liabilities Increase (Decrease) in Other Current Liabilities Inventories Increase (Decrease) in Inventories State income taxes, net of federal tax effect (c) Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Segment Reporting [Table] Segment Reporting [Table] Credit Quality Indicator [Axis] Credit Quality Indicator [Axis] Information by credit quality indicator. Lease, Cost Lease, Cost [Table Text Block] Residential Residential Customers [Member] Residential Customers [Member] Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Operating income Operating Income (Loss) Current Fiscal Year End Date Current Fiscal Year End Date Other Other Customers [Member] Other Customers [Member] Repayments under utility money pool arrangement Repayments Under Utility Money Pool Arrangement Repayments of amounts during the reporting period previously borrowed from the utility money pool borrowing arrangement among approved affiliates. Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Derivative [Line Items] Derivative [Line Items] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service cost Defined Benefit Plan, Service Cost Repayments of short-term borrowings, net Proceeds from (Repayments of) Short-Term Debt Number of complaints related to the Smokehouse Creek Complex Number of complaints related to the Smokehouse Creek Complex Number of complaints related to the Smokehouse Creek Complex Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Measure: Measure [Axis] Asset retirement obligations Asset Retirement Obligations, Noncurrent Repayments from utility money pool arrangement Repayments From Utility Money Pool Arrangement Repayments received during the reporting period of amounts previously invested into the utility money pool borrowing arrangement among approved affiliates. Equity Components [Axis] Equity Components [Axis] Debt Instrument, Repurchase Amount Debt Instrument, Repurchase Amount Smokehouse remaining liability Smokehouse remaining liability Smokehouse remaining liability Product and Service [Domain] Product and Service [Domain] Related Party Related Party [Member] Net regulatory assets and liabilities Increase (Decrease) in Regulatory Assets and Liabilities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Capitalization Capitalization, Long-Term Debt and Equity [Abstract] Entity Interactive Data Current Entity Interactive Data Current Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Deferred income taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Plant related excess deferred taxes Effective Income Tax Rate Reconciliation, Plant Related Excess Deferred Taxes, Amount Effective Income Tax Rate Reconciliation, Plant Related Excess Deferred Taxes, Amount Capital contributions from parent Proceeds from Contributions from Parent Entity Small Business Entity Small Business Total property, plant and equipment Public Utilities, Property, Plant and Equipment, Plant in Service Termination Date Trading Arrangement Termination Date Other Other Services [Member] Other Services [Member] Federal statutory rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other Other Liabilities, Current Other Other Assets, Noncurrent Document Type Document Type Debt Instrument, Repurchased Face Amount Debt Instrument, Repurchased Face Amount Derivative Asset, Current Derivative Asset, Current Series due August 15, 2036 Series due August 15, 2036 [Member] Series due August 15, 2036 Plant to be retired Public Utilities, Property, Plant And Equipment, Plant To Be Retired Public Utilities, Property, Plant And Equipment, Plant To Be Retired Fair Value as of Grant Date Award Grant Date Fair Value Materials and supplies Supplies [Member] Purchases Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Purchases Money Pool Money Pool [Member] Arrangement that allows for short-term investments in and borrowings between the utility subsidiaries. Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Common Stock, Shares Issued, Not Disclosed Common Stock, Shares Issued, Not Disclosed Common Stock, Shares Issued, Not Disclosed Arrangement Duration Trading Arrangement Duration Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Proceeds from issuance of long-term debt, net Proceeds from Issuance of Long-Term Debt Local Phone Number Local Phone Number Other Postretirement Benefits Plan [Member] Other Postretirement Benefits Plan [Member] Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Bonds Bonds [Member] Income before income taxes Income before income taxes (domestic) Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Total estimated losses and incurred costs Total estimated losses and incurred costs Total estimated losses and incurred costs Total revenues Revenues Average amount outstanding Short-Term Debt, Average Outstanding Amount Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Borrowings under utility money pool arrangement Borrowings Payable Under Utility Money Pool Arrangement Borrowings under the utility money pool borrowing arrangement among approved affiliates, which are due in one year or less in the future. Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Executive Category: Executive Category [Axis] Liabilities and Equity [Abstract] Liabilities and Equity [Abstract] Derivative Assets and Liabilities Measured at Fair Value on a Recurring Basis by Hierarchy Level Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Inventory, Net Inventory, Net All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Number of claims settled related to the Smokehouse Creek Complex Number of claims settled related to the Smokehouse Creek Complex Number of claims settled related to the Smokehouse Creek Complex Fair Value of Financial Assets and Liabilities Fair Value Disclosures [Text Block] Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Supplemental disclosure of cash flow information: Supplemental Cash Flow Information [Abstract] PEO Name PEO Name Schedule of Short-term Debt [Table] Short-Term Debt [Table] Property, Plant and Equipment, Type [Axis] Long-Lived Asset, Class [Axis] Continuing Letter of Credit Agreement Continuing Letter of Credit Agreement [Member] Continuing Letter of Credit Agreement Weighted average interest rate, computed on a daily basis Line of Credit Facility, Interest Rate During Period Number of extension you can request Number of extension you can request Number of extension you can request Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Legal Entity [Axis] Legal Entity [Axis] Lessee, Lease, Description [Table] Lessee, Lease, Description [Table] Plant related excess deferred taxes Effective Income Tax Rate Reconciliation, Plant Related Excess Deferred Taxes, Percent Effective Income Tax Rate Reconciliation, Plant Related Excess Deferred Taxes, Percent Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Accounts payable Increase (Decrease) in Accounts Payable Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] External credit rating, investment grade External Credit Rating, Investment Grade [Member] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Inventories Public Utilities, Inventory Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Management's Opinion Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Measurement Frequency [Domain] Measurement Frequency [Domain] Debt Instrument [Axis] Debt Instrument [Axis] Customer [Domain] Customer [Domain] Lessee, Operating Leases Lessee, Operating Leases [Text Block] Long-Term Debt, Type [Domain] Long-Term Debt, Type [Domain] Total current assets Assets, Current Insider Trading Arrangements [Line Items] Derivative Instruments, Gain (Loss) Derivative Instruments, Gain (Loss) [Table Text Block] Long-term debt Long-term Debt, Excluding Current Maturities Long-Term Debt, Excluding Current Maturities Award Type Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Accounts receivable, net Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current Retained earnings Retained Earnings (Accumulated Deficit) Commodity Contract [Member] Commodity Contract [Member] Short-Term Borrowings Schedule of Short-Term Debt [Table Text Block] Product and Service [Axis] Product and Service [Axis] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Pension Plan [Member] Pension Plan [Member] Short-term Debt [Line Items] Short-Term Debt [Line Items] Common Stock Common Stock [Member] Operating Lease, Cost Operating Lease, Cost Borrowings under utility money pool arrangement Borrowings Under Utility Money Pool Arrangement Borrowings made during the reporting period from the utility money pool borrowing arrangement among approved affiliates. Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Cover [Abstract] Regulated Electric Regulated Electric [Member] The core operations of the regulated electric utility segment consists of the generation, transmission, and distribution of electricity. In addition, this segment includes sales for resale and provides wholesale transmission service to other entities. Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] Weighted average interest rate at period end Short-Term Debt, Weighted Average Interest Rate, at Point in Time Derivative Contract [Domain] Derivative Contract [Domain] Public Utilities General Disclosures [Table] Public Utilities General Disclosures [Table] Equity Awards Adjustments Equity Awards Adjustments [Member] Total liabilities and equity Liabilities and Equity Employee Stock Option Share-Based Payment Arrangement, Option [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Construction work in progress Public Utilities, Property, Plant and Equipment, Construction Work in Progress Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Related Party, Type [Domain] Related and Nonrelated Parties [Domain] Accounts Receivable, Net Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Tabular List, Table Tabular List [Table Text Block] Other income, net Other Nonoperating Income (Expense) Name Awards Close in Time to MNPI Disclosures, Individual Name Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Other assets Assets, Noncurrent [Abstract] Operating and maintenance expenses Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses Property, Plant and Equipment, Type [Domain] Long-Lived Asset, Class [Domain] Changes in Level 3 Commodity Derivatives Fair Value Assets And Liabilities Measured On Recurring Basis Unobservable Input Reconciliation [Table Text Block] Tabular disclosure of the fair value measurement of net assets and liabilities using significant unobservable inputs (Level 3), a reconciliation of the beginning and ending balances, separately presenting changes during the period attributable to total gains or losses for the period (realized and unrealized), segregating those gains or losses included in earnings or recognized in other comprehensive income, purchases, sales, issuances, and settlements, and transfers in and transfers out of Level 3. Derivatives, Fair Value Derivatives, Fair Value [Line Items] Investments In Utility Money Pool Arrangement Investments In Utility Money Pool Arrangement Investments made during the reporting period into the utility money pool borrowing arrangement among approved affiliates. Adjustment to Compensation: Adjustment to Compensation [Axis] Hedging Designation [Domain] Hedging Designation [Domain] Credit Concentration Risk Credit Concentration Risk [Member] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Cash paid for interest (net of amounts capitalized) Interest Paid, Excluding Capitalized Interest, Operating Activity Utility capital/construction expenditures Payments to Acquire Productive Assets Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Credit Facility [Axis] Credit Facility [Axis] Derivative instruments Derivative Instruments and Hedges, Assets Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Maximum amount outstanding Short-Term Debt, Maximum Amount Outstanding During Period Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Accrued unbilled revenues Increase (Decrease) in Accrued Unbilled Revenues Increase (Decrease) in Accrued Unbilled Revenues Accounts payable Accounts Payable, Current Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Debt Instrument [Line Items] Debt Instrument [Line Items] Prepayments and other Increase (Decrease) in Other Current Assets Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Additional Paid In Capital Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Number of claims related to the Smokehouse Creek Complex Number of claims related to the Smokehouse Creek Complex Number of claims related to the Smokehouse Creek Complex Asset, netting Derivative Asset, Subject to Master Netting Arrangement, Gross Liability and Collateral, Obligation to Return Cash, Offset Alternative revenue and other Revenue Not from Contract with Customer Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and Cash Equivalent Series Due June 15, 2049 Series Due June 15, 2049 [Member] Series Due June 15, 2049 Company Selected Measure Amount Company Selected Measure Amount Other Derivative Instruments Not Designated as Hedging Instrument [Member] AFUDC equity Effective Income Tax Rate Reconciliation, AFUDC Equity, Percent Effective Income Tax Rate Reconciliation, AFUDC Equity, Percent Current assets Assets, Current [Abstract] Smokehouse Creek Insurance Receivable Smokehouse Creek Insurance Receivable Smokehouse Creek Insurance Receivable Non-PEO NEO Non-PEO NEO [Member] Interest charges and financing costs Interest and Debt Expense [Abstract] Entity Address, Address Line One Entity Address, Address Line One Outstanding Line of Credit Facility, Fair Value of Amount Outstanding Income tax benefit Income tax benefit Income Tax Expense (Benefit) Other Effective Income Tax Rate Reconciliation, Other Regulatory Adjustments, Percent Effective Income Tax Rate Reconciliation, Other Regulatory Adjustments, Percent Award Timing Method Award Timing Method [Text Block] Net change in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities) Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities) Pre-tax gains (losses) reclassified into income during the period from regulatory assets and (liabilities) Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Amount of insurance coverage Amount of insurance coverage Amount of insurance coverage Fuel Public Utilities, Inventory, Fuel [Member] Derivative Liability, Notional Amount Derivative Liability, Notional Amount Amortization of net loss (gain) (a) Defined Benefit Plan, Amortization of Gain (Loss) Accounting Pronouncements Accounting Standards Update and Change in Accounting Principle [Text Block] Net income Net income Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Statement [Table] Statement [Table] Environmental Remediation Site [Domain] Environmental Remediation Site [Domain] Restatement Determination Date: Restatement Determination Date [Axis] Regulatory liabilities Regulatory Liability, Current Property, Plant and Equipment, Other Types Property, Plant and Equipment, Other Types [Member] Other Effective Income Tax Rate Reconciliation, Other Regulatory Adjustments, Amount Effective Income Tax Rate Reconciliation, Other Regulatory Adjustments, Amount Total deferred credits and other liabilities Liabilities, Other than Long-Term Debt, Noncurrent Operating revenues Regulated and Unregulated Operating Revenue Derivative asset, gross Derivative Asset, Subject to Master Netting Arrangement, before Offset Borrowings and Other Financing Instruments [Abstract] Debt Instruments [Abstract] Total other assets Other Assets, Excluding Property, Plant and Equipment Sum of the carrying amounts as of the balance sheet date of all assets, excluding net property, plant and equipment, that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer. Operating revenues Revenues [Abstract] Balance at beginning of period Balance at end of period Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs Supplemental disclosure of non-cash investing and financing transactions: Other Noncash Investing and Financing Items [Abstract] Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Unsubmitted Claims related to the Smokehouse Creek Fire Complex Unsubmitted Claims related to the Smokehouse Creek Fire Complex Unsubmitted Claims related to the Smokehouse Creek Fire Complex Number of claims resolved related to the Smokehouse Creek Complex Number of claims resolved related to the Smokehouse Creek Complex Number of claims resolved related to the Smokehouse Creek Complex