Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Maximum Maximum [Member] Statistical Measurement [Domain] Statistical Measurement [Domain] Other securities at fair value Other Securities, FV-NI Other Securities, FV-NI Less: accumulated provision for depreciation and amortization Public Utilities, Property, Plant and Equipment, Accumulated Depreciation Changes in notes payable – Members, net Proceeds from (Repayments of) Notes Payable Subsequent Event Subsequent Event [Member] Debt Securities, Available-for-Sale [Table] Debt Securities, Available-for-Sale [Table] Document Fiscal Year Focus Document Fiscal Year Focus Unrealized loss Other Securities, FV-NI, Unrealized Loss Other Securities, FV-NI, Unrealized Loss Weighted average interest rate Debt, Weighted Average Interest Rate Adjustment to Compensation, Amount Adjustment to Compensation Amount Equipment Notes Equipment Notes [Member] Equipment Notes Financial Instrument [Axis] Financial Instrument [Axis] Customer [Axis] Customer [Axis] Segment Reporting [Abstract] Funds held in trust for an asset retirement obligation by Bank of Montreal as trustee for SVPL Funds Held In Trust For Asset Retirement Obligation [Member] Funds Held In Trust For Asset Retirement Obligation Depreciation, amortization and accretion Depreciation, Amortization and Accretion, Net Other byproducts Other Byproducts [Member] Other Byproducts Schedule of Long-Term Debt Instruments Schedule of Long-Term Debt Instruments [Table Text Block] First Mortgage Obilgations First Mortgage Obilgations [Member] First Mortgage Obilgations Fertilizers, urea and DEF Fertilizers, Urea and DEF [Member] Fertilizers, Urea and DEF 2007 and 2008 Notes 2007 and 2008 Notes [Member] 2007 and 2008 Notes Employee Benefit Plans Retirement Benefits [Text Block] Line of Credit Line of Credit [Member] Restatement Determination Date Restatement Determination Date Sale of investments Proceeds from Sale, Maturity and Collection of Investments Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Receivables – Members Contract with Customer, Asset, after Allowance for Credit Loss Sales - Members (related party) Sales, Members [Member] Sales, Members Derivative Instrument [Axis] Derivative Instrument [Axis] Deferred revenue Deferred Revenue [Member] Deferred Revenue Regulatory liabilities Regulatory Liability, Noncurrent Amendment Flag Amendment Flag Consolidated Entities [Axis] Consolidated Entities [Axis] Current liabilities: Liabilities, Current [Abstract] Debt and Equity Securities, FV-NI [Line Items] Debt and Equity Securities, FV-NI [Line Items] Schedule of Notional Amounts of Outstanding Derivative Positions 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 Other Debt Other Debt [Member] Other Debt Gross unrealized loss Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Loss, before Tax Investments [Domain] Investments [Domain] Other comprehensive loss: Other Comprehensive Income (Loss), Net of Tax [Abstract] Natural gas held in storage Natural Gas, Storage [Member] Ammonium sulfate Ammonium Sulfate [Member] Ammonium Sulfate Consolidated Entities [Domain] Consolidated Entities [Domain] Debt Securities, Held-to-Maturity Debt Securities, Held-to-Maturity [Table Text Block] Related Party Transactions Related Party Transactions Disclosure [Text Block] 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 PEO Total Compensation Amount PEO Total Compensation Amount Assets: Assets, Fair Value Disclosure [Abstract] Segment capital expenditure Segment Reporting, Long-Lived Asset, Expenditure for Addition Memberships Member Capital [Member] Member Capital Cash and Cash Equivalents [Abstract] Derivative, notional amount Derivative, Notional Amount Unrealized gain Other Securities, FV-NI, Unrealized Gain Other Securities, FV-NI, Unrealized Gain Wholesale Power Agreement Wholesale Power Agreement [Member] Wholesale Power Agreement Retirement Benefits [Abstract] Schedule of Related Party Transactions Schedule of Related Party Transactions [Table Text Block] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Total Capitalization and Liabilities Capitalization, Long-Term Debt and Equity Commercial Paper/Revolving Credit Agreement Commercial Paper/Revolving Credit Agreement [Member] Commercial Paper/Revolving Credit Agreement Total other assets and investments Investments and Other Noncurrent Assets Total current liabilities Liabilities, Current Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Regulatory Liability [Axis] Regulatory Liability [Axis] Other Securities Other Securities [Abstract] Other Securities Revenue from contracts with customers Revenue from Contract with Customer, Including Assessed Tax Cash flow hedge gain (loss) to be reclassified within 12 months Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Entity Address, City or Town Entity Address, City or Town Deferred charges and other: Deferred Charges And Other [Abstract] Deferred Charges And Other Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Debt Securities, Held-to-Maturity [Table] Debt Securities, Held-to-Maturity [Table] Operating activities: Operating Cash Flows, Direct Method [Abstract] Fair Value, Inputs, Level 2 Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Unrealized gain Debt Securities, Trading, and Equity Securities, Unrealized Gain Debt Securities, Trading, and Equity Securities, Unrealized Gain Laramie River Station Laramie River Station [Member] Laramie River Station MBPP operating funds Missouri Basin Power Project Operating Fund [Member] Missouri Basin Power Project Operating Fund Facility Limit Line of Credit Facility, Maximum Borrowing Capacity Other comprehensive income (loss) Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Dakota Gas Dakota Gas [Member] Dakota Gas Revenue Benchmark Revenue Benchmark [Member] Pension cost Pension Cost (Reversal of Cost) Electric Utility Electric Utility [Member] Electric Utility Subsequent Event Type [Axis] Subsequent Event Type [Axis] Concentration Risk Type [Axis] Concentration Risk Type [Axis] Schedule of Long-Term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Collateral Repurchase Agreements, Collateral, Policy [Policy Text Block] Derivative, weighted average interest rate Derivative, Average Variable Interest Rate Recently Issued Accounting Standard Updates not yet Adopted New Accounting Pronouncements, Policy [Policy Text Block] Accrued acquisition of property, plant and equipment Capital Expenditures Incurred but Not yet Paid Segment Reporting Segment Reporting [Table Text Block] Noncontrolling Interest Noncontrolling Interest [Member] Unrealized loss on cash flow hedges, tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Member Investment Program Member Investment Program [Member] Member Investment Program Use of Estimates Use of Estimates, Policy [Policy Text Block] Related and Nonrelated Parties [Axis] Related and Nonrelated Parties [Axis] Adjustment to post employment liability, tax Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Schedule of Regulatory Liabilities Schedule of Regulatory Liabilities [Table Text Block] Long-term debt Long-Term Debt Due after one year through five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year One Through Five Document Period End Date Document Period End Date 2022 Series 2022 Series [Member] 2022 Series 2012 Series 2012 Series [Member] 2012 Series 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] Dakota Coal Subsidiaries [Member] Cost Debt Securities, Trading, and Equity Securities, FV-NI, Cost Regulatory assets Regulatory Asset Total other comprehensive loss from hedging Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), after Adjustments, before Tax Interest rate, effective percentage Debt Instrument, Interest Rate, Effective Percentage Net regulatory liabilities Net Regulatory Liabilities Net Regulatory Liabilities Unrealized gain on securities, tax OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, Tax Notes receivable Financing Receivable, before Allowance for Credit Loss Interest charged during construction Interest Charged During Construction Interest Charged During Construction Liabilities Liabilities, Fair Value Disclosure Accumulated other comprehensive income Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] 2007 Series 2007 Series [Member] 2007 Series Mine related assets Mine Related Assets Mine Related Assets Cash and Cash Equivalents [Line Items] Cash and Cash Equivalents [Line Items] Statement of Comprehensive Income [Abstract] Limestone Limestone [Member] Limestone Name Outstanding Recovery, Individual Name Sales of electricity to non-members Sales Of Electricity To Non-Member [Member] Sales Of Electricity To Non-Member 2009 Series 2009 Series [Member] 2009 Series Reclassification of net realized loss on securities, tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] 2024 Series 2024 Series [Member] 2024 Series Document Fiscal Period Focus Document Fiscal Period Focus Lime Lime [Member] Lime Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Fair value Debt Securities, Trading, and Equity Securities, FV-NI Nemadji River Generation (NRG) Nemadji River Generation (NRG) [Member] Nemadji River Generation (NRG) 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] 2005 Series 2005 Series [Member] 2005 Series Total operating expenses Utilities Operating Expense Company Selected Measure Name Company Selected Measure Name Dividends paid to noncontrolling interest Payments of Ordinary Dividends, Noncontrolling Interest Restrictions on Cash and Cash Equivalents Restrictions on Cash and Cash Equivalents [Table Text Block] Coal supply Coal [Member] Other investments Other Long-Term Investments Post Employment Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Long-term debt, gross Long-Term Debt, Gross Cost Equity Securities, FV-NI, Cost Credit Facility [Domain] Credit Facility [Domain] Restricted and Designated Investment Cash, Cash Equivalent, and Investment [Table Text Block] Related Party Transactions [Abstract] Compensation Amount Outstanding Recovery Compensation Amount 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] Deferred income taxes Deferred Income Tax Charge [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] Line of Credit Facility [Table] Line of Credit Facility [Table] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Corporate commercial paper Commercial Paper [Member] Derivative Instruments and Hedging Activities Disclosure Derivative Instruments and Hedging Activities Disclosure [Text Block] Treasuries US Treasury Securities [Member] Liabilities: Investments, Fair Value Disclosure [Abstract] Regulatory Asset [Axis] Regulatory Asset [Axis] Guarantor obligations Guarantor Obligations, Current Carrying Value Electricity, December 2027 Electricity, December 2027 [Member] Electricity, December 2027 Fair Value of Liability Derivatives Derivative Liability, Subject to Master Netting Arrangement, before Offset Total deferred charges and other Assets, Noncurrent, Other than Noncurrent Investments and Property, Plant and Equipment Revenue from Contract with Customer [Abstract] Other receivables Other Receivables Current portion Long-Term Debt, Current Maturities, Gross Long-Term Debt, Current Maturities, Gross Operating lease right-of-use assets Operating Lease, Payments Restricted and designated investments Restricted Investments, Noncurrent Award Timing Predetermined Award Timing Predetermined [Flag] Debt Securities, Available-for-Sale [Line Items] Debt Securities, Available-for-Sale [Line Items] Net property, plant and equipment Public Utilities, Property, Plant and Equipment, Net Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Recognition of losses (gains) in earnings due to settlements on commodity derivatives Other Comprehensive Income (Loss), Derivative, Excluded Component, Increase (Decrease), Adjustments, before Tax Fair Value, Inputs, Level 1 Fair Value, Inputs, Level 1 [Member] Number of wholly owned for-profit subsidiaries Number of Wholly Owned For-Profit Subsidiaries Number of Wholly Owned For-Profit Subsidiaries Organization, Consolidation and Presentation of Financial Statements [Abstract] Natural Gas, December 2033 Natural Gas, December 2033 [Member] Natural Gas, December 2033 Available-for-sale debt securities: Debt Securities, Available-for-Sale [Abstract] Inventory, Current [Table] Inventory, Current [Table] All Executive Categories All Executive Categories [Member] Number of states in which entity operates Number of States in which Entity Operates Operating revenue: Regulated Operating Revenue [Abstract] Regulated Operations [Abstract] Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Restricted and designated investments Restricted Investments Screened coal Screened Coal [Member] Screened Coal Long-term debt, fair value Long-Term Debt, Fair Value Concentration Risk Type [Domain] Concentration Risk Type [Domain] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward] Accounting Changes and Error Corrections [Abstract] Fair Value Disclosures [Abstract] Unrealized gain on equity investments Unrealized Gain On Equity Investments [Member] Unrealized Gain On Equity Investments Debt Disclosure [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Change in unrealized gain (loss) on fair value hedging instruments Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments Segment Reporting Segment Reporting [Text Block] Investments Investment in Debt and Equity Securities and Other Trading Assets [Text Block] Minimum Minimum [Member] Investment Type [Axis] Investment Type [Axis] Expiration Date Trading Arrangement Expiration Date Investments Investments, Fair Value Disclosure Hedging Relationship [Axis] Hedging Relationship [Axis] Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Location, Statement of Income, Balance [Axis] Location, Statement of Income, Balance [Axis] Restricted and designated cash and equivalents Restricted Cash and Cash Equivalent Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Transmission and other misc. services Transmission And Other Miscellaneous Services [Member] Transmission And Other Miscellaneous Services Total equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Other postretirement benefits contributions (withdrawals) Other Postretirement Benefits Contributions (Withdrawals) Other Postretirement Benefits Contributions (Withdrawals) 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] Lime and limestone Lime and Limestone Inventory [Member] Lime and Limestone Inventory Nonrelated Party Nonrelated Party [Member] Net periodic expense (income) Defined Benefit Plan, Net Periodic Benefit Cost (Credit) 2016 CFC Note 2016 CFC Note [Member] 2016 CFC Note Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Derivative [Table] Derivative [Table] Recognition of initial payment for tax credits Income Tax Credits and Adjustments Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Schedule of Held-to-Maturity Securities [Line Items] Schedule of Held-to-Maturity Securities [Line Items] Unrealized loss Debt Securities, Trading, and Equity Securities, Unrealized Loss Debt Securities, Trading, and Equity Securities, Unrealized Loss Corporate and government bonds Corporate And Government Bonds [Member] Corporate And Government Bonds Exercise Price Award Exercise Price Investing activities: Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Related Party Transaction [Axis] Related Party Transaction [Axis] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Segment Reporting [Line Items] Segment Reporting [Line Items] Document Quarterly Report Document Quarterly Report Gasification Gasification [Member] Gasification 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 swaps Interest Rate Swap [Member] Proceeds from sale of AFS debt securities Proceeds from Sale of Debt Securities, Available-for-Sale Power supply Energy Service [Member] Principal payments of long-term debt Repayments of Long-Term Debt Restricted Cash and Cash Equivalents [Axis] Restricted Cash and Cash Equivalents [Axis] Unamortized debt issue costs Debt Issuance Costs, Net Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Other Equity Other Equity [Member] Other Equity Investments in associated companies Equity Method Investments Equity Component [Domain] Equity Component [Domain] Total interest and other charges Interest and other charges, net Interest Costs Incurred PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Revolving Credit Agreement Revolving Credit Agreement [Member] Revolving Credit Agreement Loans receivable, fair value Loans Receivable, Fair Value Disclosure Miscellaneous Miscellaneous [Member] Miscellaneous Changes in collateral Increase (Decrease) In Collateral Increase (Decrease) In Collateral Other income: Other Income, Nonoperating [Abstract] Adoption Date Trading Arrangement Adoption Date Counterparty Name [Domain] Counterparty Name [Domain] Equity attributable to parent Equity, Attributable to Parent Total other income Other (income) expense Nonoperating Income (Expense) Settlements Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement 2015 Series 2015 Series [Member] 2015 Series 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 Cost Debt Securities, Available-for-Sale, Amortized Cost Accounting Policies [Abstract] Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Insider Trading Policies and Procedures [Line Items] Other Proceeds from (Payment for) Other Financing Activity Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] 2011 Series 2011 Series [Member] 2011 Series Schedule of Line of Credit Facilities Schedule of Line of Credit Facilities [Table Text Block] Prepayments and other current assets Prepaid Expense and Other Assets, Current Deferred income taxes Deferred Income Tax Expense (Benefit) Nonelectric selling, general and administrative (includes related party of $8,407 and $7,547, respectively) Nonelectric selling, general and administrative Selling, General and Administrative Expense Selected Balance Sheet Information Supplemental Balance Sheet Disclosures [Text Block] Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Table] Segment Reporting, Entity-Wide Information Not Provided as Part of Reportable Segment, Customer, Extent of Reliance [Table] Number of wholly owned not-for-profit subsidiaries Number of Wholly Owned Not-For-Profit Subsidiaries Number of Wholly Owned Not-For-Profit Subsidiaries Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Water supply Water Supply [Member] Water Supply Central Index Key Entity Central Index Key Regulatory Liability [Line Items] Regulatory Liability [Line Items] Notes payable Notes Payable, Current All Adjustments to Compensation All Adjustments to Compensation [Member] Other Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Other operating activities, net Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Other Item Equity: Equity [Abstract] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Other equity Stockholders' Equity, Other Income Statement [Abstract] 2008 Series 2008 Series [Member] 2008 Series Document Transition Report Document Transition Report Ownership [Axis] Ownership [Axis] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Designated as Hedging Instrument Designated as Hedging Instrument [Member] Asset retirement obligations Assets Retirement Obligations [Member] Assets Retirement Obligations Operating expenses: Operating Expenses [Abstract] Contracted Monthly Volumes of Forecasted Transactions Derivative, Nonmonetary Notional Amount, Percent of Required Need, Coverage Finance lease obligations Finance Lease, Liability, Noncurrent Intersegment Eliminations Intersegment Eliminations [Member] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Patronage capital Patronage Capital Patronage Capital 2025 Series 2025 Series [Member] 2025 Series Patronage capital allocated Patronage Capital Allocated Patronage Capital Allocated City Area Code City Area Code Post-retirement medical gain Postretirement Benefit Costs [Member] Accumulated Other Comprehensive Income AOCI Attributable to Parent [Member] All Individuals All Individuals [Member] Subsequent Events Subsequent Events [Text Block] Name Forgone Recovery, Individual Name Regulatory Liability [Domain] Regulatory Liability [Domain] Balance Sheet Related Disclosures [Abstract] Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Statement [Line Items] Statement [Line Items] Assets Assets Assets Entity [Domain] Entity [Domain] Investment income Investment Income, Net Variable Interest Entity, Not Primary Beneficiary Variable Interest Entity, Not Primary Beneficiary [Member] Amortization of prior service cost Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Operating Segments Operating Segments [Member] Interest expense Interest Expense, Nonoperating Gross unrealized gain Debt Securities, Available-for-Sale, Accumulated Gross Unrealized Gain, before Tax Energy [Domain] Energy [Domain] Weighted average interest rate Loan Receivable, Weighted Average Interest Rate Loan Receivable, Weighted Average Interest Rate Nemadji Trail Energy Center (NTEC) Nemadji Trail Energy Center (NTEC) [Member] Nemadji Trail Energy Center (NTEC) Organization Nature of Operations [Text Block] PEO PEO [Member] Cash surrender value of life insurance Cash Surrender Value of Life Insurance Urea Urea [Member] Urea Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Other noncurrent liabilities Other Liabilities, Noncurrent Jointly Owned Electricity Generation Plant Jointly Owned Electricity Generation Plant [Member] 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 Due through one year Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, Year One Subsequent Event Type [Domain] Subsequent Event Type [Domain] Special funds Special Funds Special Funds Retained Earnings of Subsidiaries Retained Earnings [Member] Revolving Credit Facility Revolving Credit Facility [Member] Money market funds Money Market Funds [Member] Unrealized Gain on Securities AOCI, Accumulated Gain (Loss), Debt Securities, Available-for-Sale, Parent [Member] Fair Value Measurement Fair Value Measurement, Policy [Policy Text Block] Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Unrealized gain on securities (net of tax of $5 and $49, respectively) OCI, Debt Securities, Available-for-Sale, Unrealized Holding Gain (Loss), before Adjustment, after Tax Award Timing Disclosures [Line Items] Payment of debt issuance costs Payments of Debt Issuance Costs Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash (used in) provided by financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Project and other services Project And Other Services [Member] Project And Other Services Total Shareholder Return Amount Total Shareholder Return Amount Intersegment Intersubsegment Eliminations [Member] Prepayments and other current assets Increase (Decrease) in Prepaid Expense and Other Assets Investments: Liabilities, Fair Value Disclosure [Abstract] Cash Flow Hedging Cash Flow Hedging [Member] Unrealized loss on investments Unrealized Gain (Loss) on Investments Diesel purchases Fuel [Member] Inventory [Domain] Inventory [Domain] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Debt Securities, Equity, and Other Securities Debt Securities, Trading, and Equity Securities, FV-NI [Abstract] Ownership [Domain] Ownership [Domain] Electric operations and maintenance (includes related party of $(2,317) and $(1,651), respectively Electric operations and maintenance Electric operations and maintenance Utilities Operating Expense, Maintenance and Operations Adjustments to reconcile net margin and earnings to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Cost Other Securities, FV-NI, Cost Other Securities, FV-NI, Cost Natural gas Natural Gas [Member] Financing activities: Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Total operating revenues Other operating revenues Revenue from Contract with Customer, Excluding Assessed Tax Coal and fuel oil Public Utilities Inventory, Coal and Fuel Oil [Member] Public Utilities Inventory, Coal and Fuel Oil Line of credit Line of Credit, Current Interest cost Defined Benefit Plan, Interest Cost Financial Instruments [Domain] Financial Instruments [Domain] Refinancing fees Refinancing Fees [Member] Refinancing Fees Due after five years Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Debt Securities, Available-for-Sale, Fair Value, Maturity, Allocated and Single Maturity Date, after Year 5 Commodity derivatives Derivative Asset Tar Oil, December 2027 Tar Oil, December 2027 [Member] Tar Oil, December 2027 2024 CoBank Note 2024 CoBank Note [Member] 2024 CoBank Note Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Net (decrease) increase in cash and cash equivalents and restricted and designated cash and cash equivalents Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), 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investments, net Payment for (Proceeds from) Other Investing Activity Inventories Increase (Decrease) in Inventories Administrative services Administrative Service [Member] Segment Reporting [Table] Segment Reporting [Table] Related Party Transaction [Table] Related Party Transaction [Table] Equity Method Investment [Table] Equity Method Investment [Table] 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] Reclassification of net realized loss (gain) on cash flow hedges, tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Operating margin Operating Income (Loss) Current Fiscal Year End Date Current Fiscal Year End Date Held-to-maturity securities at amortized cost Debt Securities, Held-to-Maturity, Amortized Cost, before Allowance for Credit Loss Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Derivative [Line Items] Derivative [Line Items] Related Party Transaction [Domain] Related Party Transaction [Domain] External Reportable Subsegments [Member] 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 Average floor price Derivative, Average Floor Price Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Service cost Defined Benefit Plan, Service Cost Changes in other operating elements: Additional Cash Flow Elements, Operating Activity [Abstract] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Schedule of Collateral Posted at Fair Value Schedule Of Collateral Posted At Fair Value [Table Text Block] Schedule Of Collateral Posted At Fair Value Dividends paid to noncontrolling interest Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Long-term debt and finance leases due within one year Long-Term Debt And Lease Obligation, Excluding Notes Payable Long-Term Debt And Lease Obligation, Excluding Notes Payable 2023 Note 2023 Note [Member] 2023 Note Amount reclassified from accumulated other comprehensive income into net margins and earnings Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax Bond market funds Bond Market Funds [Member] Bond Market Funds Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Restricted Cash and Cash Equivalent Item [Line Items] Restricted Cash and Cash Equivalent Item [Line Items] Measure: Measure [Axis] Unrealized gain Equity Securities, FV-NI, Unrealized Gain Debt securities, AFS, allowance for credit loss Debt Securities, Available-for-Sale, Allowance for Credit Loss Accumulated Other Comprehensive Income Comprehensive Income (Loss) Note [Text Block] Lignite coal Lignite Coal [Member] Lignite Coal 2025 Term Loan 2025 Term Loan [Member] 2025 Term Loan Equity Components [Axis] Equity Components [Axis] Product and Service [Domain] Product and Service [Domain] Related Party Related Party [Member] Cash paid for income taxes Income Tax Paid, after Refund Received Changes in regulatory assets and liabilities Increase (Decrease) in Regulatory Assets and Liabilities Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Remaining Recovery Period Remaining Recovery Period of Regulatory Assets for which No Return on Investment During Recovery Period is Provided Capitalization and Liabilities Capitalization, Long-Term Debt and Equity [Abstract] Entity Interactive Data Current Entity Interactive Data Current Net margin and earnings attributable to noncontrolling interest Net margin and earnings attributable to noncontrolling interest Net Income (Loss) Attributable 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Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activity Capital expenditures Payments to Acquire Productive Assets Statement of Cash Flows [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Assets Assets, Fair Value Disclosure Regulatory Assets and Liabilities Schedule of Regulatory Assets and Liabilities [Text Block] 2017 Series 2017 Series [Member] 2017 Series Name Measure Name Fertilizer and DEF products Fertilizer and DEF Products [Member] Fertilizer and DEF Products Cash and Cash Equivalent [Table] Cash and Cash Equivalent [Table] 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] Depreciation, depletion and amortization Depreciation, Depletion and Amortization, Including Utilities Operating Expense Depreciation, Depletion and Amortization, Including Utilities Operating Expense Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Equity Purchase Agreement Equity Purchase Agreement [Member] Equity Purchase Agreement Electric fuel and purchased power Utilities Operating Expense, Electric Fuel And Purchased Power Utilities Operating Expense, Electric Fuel And Purchased Power Retirement Plan Type [Domain] Retirement Plan Type [Domain] Entity Filer Category Entity Filer Category Supplemental cash flow information: Supplemental Cash Flow Elements [Abstract] Short-term investments Short-Term Investments Other Other Regulatory Assets (Liabilities) [Member] Missouri Basin Power Project (MBPP) Missouri Basin Power Project (MBPP) [Member] Missouri Basin Power Project (MBPP) Other revenue Revenue Not from Contract with Customer Name Trading Arrangement, Individual Name Schedule of Regulatory Assets Schedule of Regulatory Assets [Table Text Block] Cash and cash equivalents Cash and Cash Equivalent Energy [Axis] Energy [Axis] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Company Selected Measure Amount Company Selected Measure Amount Not Designated as Hedging Instrument Not Designated as Hedging Instrument [Member] Diesel, January 2029 Diesel, January 2029 [Member] Diesel, January 2029 Investments, Debt and Equity Securities [Abstract] Dakota Coal Dakota Coal [Member] Dakota Coal Net margin and earnings including noncontrolling interest Net margin and earnings including noncontrolling interest Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Current assets: Assets, Current [Abstract] Derivative liability Derivative Liability Non-PEO NEO Non-PEO NEO [Member] Entity Address, Address Line One Entity Address, Address Line One Income tax expense Income Tax Expense (Benefit) Total amounts of income and expense line items presented on the consolidated statements of operations in which the effects of cash flow hedges are recorded Gain (loss) on fair value hedges recognized in earnings Gain (Loss) on Fair Value Hedges Recognized in Earnings Customer Concentration Risk Customer Concentration Risk [Member] Cost of products sold (includes related party of $20,187 and $16,802, respectively) Good and services provided Cost of Product and Service Sold Award Timing Method Award Timing Method [Text Block] Equity Funds Equity Funds [Member] Principles of Consolidation Consolidation, Policy [Policy Text Block] Other operating revenues Other Product and Service, Other [Member] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] 2006 Series 2006 Series [Member] 2006 Series Memberships Members' Capital Amortization of net actuarial gain Defined Benefit Plan, Amortization of Gain (Loss) New Accounting Pronouncements Accounting Standards Update and Change in Accounting Principle [Text Block] Net margin and earnings attributable to Basin Electric Net margin and earnings attributable to Basin Electric Net Income (Loss) Attributable to Parent Long-Term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Location, Statement of Financial Position, Balance [Axis] Location, Statement of Financial Position, Balance [Axis] Proceeds from sales of property Proceeds from Sale of Property, Plant, and Equipment Statement [Table] Statement [Table] Plant in service Public Utilities, Property, Plant and Equipment, Plant in Service (Excluding Construction Work in Process) Public Utilities, Property, Plant and Equipment, Plant in Service (Excluding Construction Work in Process) Restatement Determination Date: Restatement Determination Date [Axis] Schedule of Accumulated Other 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