Basis of Presentation (Policies)	3 Months Ended
Mar. 31, 2026
Accounting Policies [Abstract]
Principles of Consolidation	PRINCIPLES OF CONSOLIDATION–The consolidated financial statements include the accounts of Basin Electric, its wholly owned subsidiaries and its VIE’s, Coteau and DCS. DCS is considered a VIE for which Dakota Gas is the primary beneficiary. All intercompany investments, debt, and receivable and payable accounts have been eliminated in consolidation. Charges from BCS, Dakota Gas, Dakota Coal, MLC and Coteau to Basin Electric and charges from Basin Electric to BCS, Dakota Gas, Dakota Coal, MLC and Coteau are not eliminated as Basin Electric includes the results of these activities in the determination of rates charged to its members (Note 16). N-7 LLC (N-7) is a Delaware limited liability company formed by OCI Iowa, Inc. (OCI) and Dakota Gas on May 18, 2018. N-7 was formed to market OCI’s, Dakota Gas’s and other companies’ fertilizer and DEF production. N-7 is considered a VIE of Dakota Gas for which Dakota Gas is not the primary beneficiary and, therefore, Dakota Gas is not required to consolidate N-7. However, Dakota Gas has the ability to exercise significant influence over N-7. Therefore, Dakota Gas’s share of N-7 net income is recorded in the consolidated financial statements using the equity method of accounting. The investment in N-7 is included in other investments on the consolidated balance sheets and Dakota Gas’ share of N-7 net income is presented in other and tax credits income in the consolidated statements of operations. In 2024, Dakota Gas and OCI agreed to dissolve N-7 with final dissolution to be completed in 2026. Basin Electric does not anticipate this to have a material impact on the consolidated financial statements and disclosures.
Use of Estimates	USE OF ESTIMATES–The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Estimates are used for items such as present value of lease assets and lease liabilities, plant depreciable lives, actuarially determined benefit costs, valuation of derivatives, asset retirement obligations, present value of expected tax credits, cash flows used in asset impairment evaluations and income tax expense or benefits. Ultimate results could differ from those estimates.
Interim Financial Information	INTERIM FINANCIAL INFORMATION–Basin Electric’s consolidated interim financial statements are unaudited, and reflect all adjustments management considers necessary (consisting of normal recurring accruals) for a fair presentation. The Financial Statements included herein have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, we believe that the condensed disclosures provided are adequate to make the information presented not misleading. Basin Electric’s operating results are affected by various factors including sales to members which may vary with weather conditions, the availability and market for sales of surplus power, actions of the Basin Electric board of directors in their role as regulator, general business conditions, the demand for non-utility products and services produced by Dakota Gas, Dakota Coal and Basin Electric’s other subsidiary companies and availability of substitute products in the market, and operating costs which vary based on plant outages, labor conditions and other costs of production. Accordingly, Basin Electric’s operating results for the three-month periods ended March 31, 2026 and 2025 are not necessarily an appropriate base from which to project annual results. The consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes included in Basin Electric’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on May 6, 2026 (the Prospectus). There have been no changes to Basin Electric’s significant accounting policies described in the Prospectus that have had a material impact on Basin Electric’s consolidated interim financial statements and related notes.
Recently Issued Accounting Standard Updates not yet Adopted	RECENTLY ISSUED ACCOUNTING STANDARD UPDATES (ASU) NOT YET ADOPTED ASU No. 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures: Disaggregation of Income Statement Expenses – In November 2024, the FASB issued new guidance to improve disclosures about a public business entity’s expenses that will require additional detail for certain categories of income statement expenses. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted and the new guidance is to be applied either on a prospective or retrospective basis. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures. ASU No. 2025-06, Intangibles-Goodwill and Other-Internal-Use Software: Targeted Improvements to the Accounting for Internal-Use Software – In September 2025, the FASB issued new guidance to modernize existing older guidance regarding capitalization and recognition to reflect the software development approaches currently being utilized. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied using one of the three prescribed approaches. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures. ASU No. 2025-09, Derivatives and Hedging: Hedge Accounting Improvements – In November 2025, the FASB issued new guidance in an effort to better reflect an entity's risk management activities in the financial statements. The update makes targeted improvements by addressing five specific matters that arose from the implementation of previous ASU 2017-12, Derivatives and Hedging: Targeted Improvements for Accounting for Hedging Activities and the effects of LIBOR cessation. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied on a prospective basis, although an entity may elect to adopt the guidance for hedging relationships that exist as of the date of adoption. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures. ASU No. 2025-10, Government Grants: Accounting for Government Grants Received by Business Entities – In December 2025, the FASB issued new guidance to improve GAAP by establishing authoritative guidance on the accounting for government grants received by business entities. Previously, GAAP did not provide specific guidance about the recognition, measurement, and presentation of a grant received by a business entity from a government, and due to this absence of specific guidance, Basin Electric like many other business entities, utilized the guidance contained in IAS 20, Accounting for Government Grants and Disclosure of Government Assistance. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied using one of the three prescribed approaches. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures.
Collateral	COLLATERAL-Certain derivative instruments and certain agreements of Basin Electric and Dakota Gas contain contract provisions that require collateral to be posted if the credit ratings of Basin Electric fall below certain levels or if the counterparty exposure to Basin Electric or Dakota Gas exceeds a certain level.
Fair Value Measurement	Level 1 inputs utilize observable market data in active markets for identical assets or liabilities. Level 2 inputs consist of observable market data, other than that included in Level 1, that is either directly or indirectly observable. Level 3 inputs consist of unobservable market data which are typically based on an entity’s own assumptions of what a market participant would use in pricing an asset or liability as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Basin Electric’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability. On March 31, 2026 and December 31, 2025, Basin Electric had government obligations, equity securities, bond market funds and corporate bonds included in restricted and designated investments, mine related assets and other investments, recorded at a fair value, using quoted prices in active markets for identical assets as the fair value measurement (Level 1). Basin Electric recorded derivative financial instruments including commodity contracts and interest rate swaps using significant other observable inputs as the fair value measurement (Level 2). The fair value for commodity contracts is determined by comparing the difference between the net present value of the cash flows for the commodity contracts at their initial price and the current market price. The initial price is quoted in the commodity contract and the current market price is corroborated by observable market data. The fair value for interest rate swap contracts is determined by comparing the difference between the net present value of the cash flows for the swaps at their initial fixed rate and the current market interest rate. The initial fixed rate is quoted in the swap agreement and the current market interest rate is corroborated by observable market data.

Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2026

PRINCIPLES OF CONSOLIDATION–The consolidated financial statements include the accounts of Basin Electric, its wholly owned subsidiaries and its VIE’s, Coteau and DCS. DCS is considered a VIE for which Dakota Gas is the primary beneficiary. All intercompany investments, debt, and receivable and payable accounts have been eliminated in consolidation. Charges from BCS, Dakota Gas, Dakota Coal, MLC and Coteau to Basin Electric and charges from Basin Electric to BCS, Dakota Gas, Dakota Coal, MLC and Coteau are not eliminated as Basin Electric includes the results of these activities in the determination of rates charged to its members (Note 16).

N-7 LLC (N-7) is a Delaware limited liability company formed by OCI Iowa, Inc. (OCI) and Dakota Gas on May 18, 2018. N-7 was formed to market OCI’s, Dakota Gas’s and other companies’ fertilizer and DEF production. N-7 is considered a VIE of Dakota Gas for which Dakota Gas is not the primary beneficiary and, therefore, Dakota Gas is not required to consolidate N-7. However, Dakota Gas has the ability to exercise significant influence over N-7. Therefore, Dakota Gas’s share of N-7 net income is recorded in the consolidated financial statements using the equity method of accounting. The investment in N-7 is included in other investments on the consolidated balance sheets and Dakota Gas’ share of N-7 net income is presented in other and tax credits income in the consolidated statements of operations.

In 2024, Dakota Gas and OCI agreed to dissolve N-7 with final dissolution to be completed in 2026. Basin Electric does not anticipate this to have a material impact on the consolidated financial statements and disclosures.

Use of Estimates

USE OF ESTIMATES–The preparation of consolidated financial statements in conformity with accounting principles generally accepted in the United States of America (GAAP) requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Estimates are used for items such as present value of lease assets and lease liabilities, plant depreciable lives, actuarially determined benefit costs, valuation of derivatives, asset retirement obligations, present value of expected tax credits, cash flows used in asset impairment evaluations and income tax expense or benefits. Ultimate results could differ from those estimates.

Interim Financial Information

INTERIM FINANCIAL INFORMATION–Basin Electric’s consolidated interim financial statements are unaudited, and reflect all adjustments management considers necessary (consisting of normal recurring accruals) for a fair presentation. The Financial Statements included herein have been prepared pursuant to the rules and regulations of the U.S. Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with GAAP have been condensed or omitted pursuant to such rules and regulations; however, we believe that the condensed disclosures provided are adequate to make the information presented not misleading. Basin Electric’s operating results are affected by various factors including sales to members which may vary with weather conditions, the availability and market for sales of surplus power, actions of the Basin Electric board of directors in their role as regulator, general business conditions, the demand for non-utility products and services produced by Dakota Gas, Dakota Coal and Basin Electric’s other subsidiary companies and availability of substitute products in the market, and operating costs which vary based on plant outages, labor conditions and other costs of production. Accordingly, Basin Electric’s operating results for the three-month periods ended March 31, 2026 and 2025 are not necessarily an appropriate base from which to project annual results.

The consolidated interim financial statements should be read in conjunction with the audited consolidated financial statements and notes included in Basin Electric’s final prospectus filed with the SEC pursuant to Rule 424(b) under the Securities Act of 1933, as amended, on May 6, 2026 (the Prospectus). There have been no changes to Basin Electric’s significant accounting policies described in the Prospectus that have had a material impact on Basin Electric’s consolidated interim financial statements and related notes.

Recently Issued Accounting Standard Updates not yet Adopted

RECENTLY ISSUED ACCOUNTING STANDARD UPDATES (ASU) NOT YET ADOPTED

ASU No. 2024-03, Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures: Disaggregation of Income Statement Expenses – In November 2024, the FASB issued new guidance to improve disclosures about a public business entity’s expenses that will require additional detail for certain categories of income statement expenses. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2026, and interim reporting periods beginning after December 15, 2027. Early adoption is permitted and the new guidance is to be applied either on a prospective or retrospective basis. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures.

ASU No. 2025-06, Intangibles-Goodwill and Other-Internal-Use Software: Targeted Improvements to the Accounting for Internal-Use Software – In September 2025, the FASB issued new guidance to modernize existing older guidance regarding capitalization and recognition to reflect the software development approaches currently being utilized. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2027, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied using one of the three prescribed approaches. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures.

ASU No. 2025-09, Derivatives and Hedging: Hedge Accounting Improvements – In November 2025, the FASB issued new guidance in an effort to better reflect an entity's risk management activities in the financial statements. The update makes targeted improvements by addressing five specific matters that arose from the implementation of previous ASU 2017-12, Derivatives and Hedging: Targeted Improvements for Accounting for Hedging Activities and the effects of LIBOR cessation. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied on a prospective basis, although an entity may elect to adopt the guidance for hedging relationships that exist as of the date of adoption. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures.

ASU No. 2025-10, Government Grants: Accounting for Government Grants Received by Business Entities – In December 2025, the FASB issued new guidance to improve GAAP by establishing authoritative guidance on the accounting for government grants received by business entities. Previously, GAAP did not provide specific guidance about the recognition, measurement, and presentation of a grant received by a business entity from a government, and due to this absence of specific guidance, Basin Electric like many other business entities, utilized the guidance contained in IAS 20, Accounting for Government Grants and Disclosure of Government Assistance. The new guidance will be effective for Basin Electric for annual reporting periods beginning after December 15, 2028, and interim reporting periods within those annual reporting periods. Early adoption is permitted and the new guidance is to be applied using one of the three prescribed approaches. Management is currently evaluating the impact of adoption of this new guidance on the financial statements and disclosures.

Collateral

COLLATERAL-Certain derivative instruments and certain agreements of Basin Electric and Dakota Gas contain contract provisions that require collateral to be posted if the credit ratings of Basin Electric fall below certain levels or if the counterparty exposure to Basin Electric or Dakota Gas exceeds a certain level.

Fair Value Measurement

Level 1 inputs utilize observable market data in active markets for identical assets or liabilities. Level 2 inputs consist of observable market data, other than that included in Level 1, that is either directly or indirectly observable. Level 3 inputs consist of unobservable market data which are typically based on an entity’s own assumptions of what a market participant would use in pricing an asset or liability as there is little, if any, related market activity. In instances where the determination of the fair value measurement is based on inputs from different levels of the fair value hierarchy, the level in the fair value hierarchy within which the entire fair value measurement falls is based on the lowest level input that is significant to the fair value measurement in its entirety. Basin Electric’s assessment of the significance of a particular input to the fair value measurement in its entirety requires judgment, and considers factors specific to the asset or liability.

On March 31, 2026 and December 31, 2025, Basin Electric had government obligations, equity securities, bond market funds and corporate bonds included in restricted and designated investments, mine related assets and other investments, recorded at a fair value, using quoted prices in active markets for identical assets as the fair value measurement (Level 1).

Basin Electric recorded derivative financial instruments including commodity contracts and interest rate swaps using significant other observable inputs as the fair value measurement (Level 2). The fair value for commodity contracts is determined by comparing the difference between the net present value of the cash flows for the commodity contracts at their initial price and the current market price. The initial price is quoted in the commodity contract and the current market price is corroborated by observable market data. The fair value for interest rate swap contracts is determined by comparing the difference between the net present value of the cash flows for the swaps at their initial fixed rate and the current market interest rate. The initial fixed rate is quoted in the swap agreement and the current market interest rate is corroborated by observable market data.