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Variable Interest Entities (Details) - USD ($) $ in Thousands | Dec. 31, 2025 | Dec. 31, 2024
--- | --- | ---
Variable Interest Entity [Line Items] |  |  |
In-service utility plant, net |  | $ 2,279,899 | $ 2,149,138
Construction work in progress |  | 292,969 | 138,208
Accrued interest and accrued (prepaid) taxes |  | 10,269 | 11,558
Deferred income taxes |  | 337,798 | 316,397
Unamortized discount and debt issuance costs |  | 4,277 | 4,419
MGE Power Elm Road [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
In-service utility plant, net |  | 157,652 | 159,576
Construction work in progress |  | 485 | 514
Other Receivables |  | $ 0 | $ 0
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration] |  | Affiliated Entity [Member] | Affiliated Entity [Member]
Accrued interest and accrued (prepaid) taxes |  | $ (129) | $ (184)
Deferred income taxes |  | 31,153 | 30,902
Long-term debt | [1] | 38,447 | 41,082
Noncontrolling interest |  | 104,479 | 104,304
Unamortized discount and debt issuance costs |  | 200 | 200
MGE Power West Campus [Member] |  |  |
Variable Interest Entity [Line Items] |  |  |
In-service utility plant, net |  | 78,970 | 76,378
Construction work in progress |  | 4,174 | 3,052
Other Receivables |  | $ 861 | $ 911
Other Receivable, after Allowance for Credit Loss, Related Party [Extensible Enumeration] |  | Affiliated Entity [Member] | Affiliated Entity [Member]
Accrued interest and accrued (prepaid) taxes |  | $ (46) | $ (78)
Deferred income taxes |  | 15,601 | 15,435
Long-term debt | [1] | 25,941 | 28,550
Noncontrolling interest |  | 52,309 | 46,082
Unamortized discount and debt issuance costs |  | $ 100 | $ 100
[1] | MGE Power Elm Road's long-term debt includes debt issuance costs of $0.2 million as of December 31, 2025 and 2024. The debt is secured by a collateral assignment of lease payments that MGE makes to MGE Power Elm Road for use of the Elm Road Units pursuant to the related long-term leases. MGE Power West Campus's long-term debt includes debt issuance costs of $0.1 million as of December 31, 2025 and 2024. The debt is secured by a collateral assignment of lease payments that MGE makes to MGE Power West Campus for use of the cogeneration facility pursuant to the long-term lease. See Footnote 14 for further information on the long-term debt securities.

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