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Investments (Tables) | 12 Months Ended
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Dec. 31, 2025
Investments Disclosure [Abstract] |
Equity Method and Other Investments | a. Equity Securities, Equity Method Investments, and Other Investments.
|  | MGE Energy |
(In thousands) |  | 2025 |  |  | 2024 |
Equity securities |  | $ | 22,591 |  |  | $ | 23,119 |
Equity method investments: |  |  |  |  |  |
ATC and ATC Holdco |  |  | 102,985 |  |  |  | 92,579 |
Other |  |  | 39 |  |  |  | 39 |
Total equity method investments |  |  | 103,024 |  |  |  | 92,618 |
Other investments |  |  | 2,298 |  |  |  | 2,298 |
Total |  | $ | 127,913 |  |  | $ | 118,035 |
For the years ended December 31, 2025, 2024, and 2023, there were no material liquidated investments for MGE. For the years ended December 31, 2025, 2024, and 2023, certain investments were liquidated for MGE Energy. As a result of these liquidations, the following was received:
(In thousands) |  | 2025 |  |  | 2024 |  |  | 2023 |
Cash proceeds |  | $ | 4,497 |  |  | $ | 2,554 |  |  | $ | 995 |
Gain (loss) on sale |  |  | 3,263 |  |  |  | 239 |  |  |  | (899 | )
Equity Method Investments Summarized Financial Data | For the following years ended December 31, MGE Transco recorded the following:
(In thousands) |  | 2025 |  |  | 2024 |  |  | 2023 |
Equity earnings from investment in ATC |  | $ | 12,682 |  |  | $ | 12,498 |  |  | $ | 10,515 |
Dividends received from ATC |  |  | 10,612 |  |  |  | 8,635 |  |  |  | 8,397 |
Capital contributions to ATC |  |  | 8,385 |  |  |  | 2,679 |  |  |  | 3,750 |
ATC's summarized financial data is as follows:
(In thousands) |  |  |  |  |  |  |  |  |
Income statement data for the year ended December 31, |  | 2025 |  |  | 2024 |  |  | 2023 |
Operating revenues |  | $ | 974,956 |  |  | $ | 911,314 |  |  | $ | 818,921 |
Operating expenses |  |  | (472,610 | ) |  |  | (442,359 | ) |  |  | (407,643 | )
Other income |  |  | 1,364 |  |  |  | 1,407 |  |  |  | 2,452 |
Interest expense, net |  |  | (167,152 | ) |  |  | (139,204 | ) |  |  | (134,107 | )
Earnings before members' income taxes |  | $ | 336,558 |  |  | $ | 331,158 |  |  | $ | 279,623 |
Balance sheet data as of December 31, |  | 2025 |  |  | 2024 |  |  |  |
Current assets |  | $ | 137,522 |  |  | $ | 126,628 |  |  |  |
Noncurrent assets |  |  | 7,590,778 |  |  |  | 6,792,600 |  |  |  |
Total assets |  | $ | 7,728,300 |  |  | $ | 6,919,228 |  |  |  |
Current liabilities |  | $ | 839,789 |  |  | $ | 482,440 |  |  |  |
Long-term debt |  |  | 3,156,253 |  |  |  | 3,083,409 |  |  |  |
Other noncurrent liabilities |  |  | 638,916 |  |  |  | 544,973 |  |  |  |
Members' equity |  |  | 3,093,342 |  |  |  | 2,808,406 |  |  |  |
Total members' equity and liabilities |  | $ | 7,728,300 |  |  | $ | 6,919,228 |  |  |  |

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- Definition Tabular disclosure of equity method investments in common stock and other investments. The equity method investments disclosure may include: (a) the name of each investee or group of investments for which combined disclosure is appropriate, (2) the percentage ownership of common stock, (3) the difference, if any, between the carrying amount of an investment and the value of the underlying equity in the net assets and the accounting treatment of difference, if any, and (4) the aggregate value of each identified investment based on its quoted market price, if available. + References No definition available. + Details
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- Definition Tabular disclosure of equity method investments including, but not limited to, name of each investee or group of investments, percentage ownership, difference between recorded amount of an investment and the value of the underlying equity in the net assets, and summarized financial information. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 323 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481687/323-10-50-3 + Details
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