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Rate Matters (Details) - USD ($) $ in Thousands | 1 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Oct. 31, 2021 | Sep. 30, 2021 | Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020 | Dec. 31, 2019
Fuel Rules [Abstract] |  |  |  |  |  |  |
Deferred fuel rules monitored costs |  | $ 0 |  |  |  |  | $ 1,500
Rate Matters For Future Periods [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Proposed return on equity, percentage |  |  |  | 9.80% |  |  |
Proposed equity capital structure, percentage |  |  |  | 55.60% |  |  |
PSCW [Member] | MGE [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Authorized return on equity, percentage |  | 9.80% |  |  |  | 9.80% | 9.80%
Approved equity capital structure, percentage |  | 55.80% |  |  |  | 56.10% | 56.60%
Fuel Rules [Abstract] |  |  |  |  |  |  |
Fuel rules, bandwidth |  | 1.00% |  |  |  | 2.00% |
Fuel rules, electric fuel deferred costs upper threshold |  | 101.00% |  |  |  |  |
Fuel rules, electric fuel deferred costs lower threshold |  | 99.00% |  |  |  |  |
PSCW [Member] | MGE [Member] | Fuel Rules Refund, 2020 [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Fuel Rules [Abstract] |  |  |  |  |  |  |
Return of electric fuel credit, total | $ 3,200 |  |  |  |  |  |
Electric Rate Proceeding [Member] | Rate Matters For Future Periods [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Proposed rate increase (decrease), percentage |  |  |  | 5.16% |  |  |
Electric Rate Proceeding [Member] | PSCW [Member] | MGE [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Authorized rate increase (decrease), percentage |  | 0.00% |  |  |  | (0.84%) | (2.24%)
Authorized rate increase (decrease), amount |  |  |  |  |  | $ (3,400) | $ (9,200)
Electric Rate Proceeding [Member] | PSCW [Member] | Rate Matters For Future Periods [Member] | MGE [Member] |  |  |  |  |  |  |
Effects Of The Tax Cuts And Jobs Act [Abstract] |  |  |  |  |  |  |
Return of unprotected excess deferred taxes |  |  |  |  | $ 18,200 |  |
Gas Rate Proceeding [Member] | Rate Matters For Future Periods [Member] | Subsequent Event [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Proposed rate increase (decrease), percentage |  |  | 0.96% | 2.15% |  |  |
Gas Rate Proceeding [Member] | PSCW [Member] | MGE [Member] |  |  |  |  |  |  |
Rate Proceedings [Abstract] |  |  |  |  |  |  |
Authorized rate increase (decrease), percentage |  | 4.00% |  |  |  | 1.46% | 1.06%
Authorized rate increase (decrease), amount |  |  |  |  |  | $ 2,400 | $ 1,700

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- Definition The amount of electric fuel rules monitored costs which have been deferred outside the symmetrical cost tolerance band authorized by a regulatory agency. + References No definition available. + Details
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- Definition Pursuant to the provisions of the rate order, the fuel rules bandwidth will be plus or minus this percentage. + References No definition available. + Details
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- Definition Under fuel rules, the amount in which MGE is required to defer the benefit of lower costs if actual electric fuel costs were less than the allowed electric fuel costs in latest rate order. + References No definition available. + Details
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- Definition Under fuel rules, the amount in which MGE would defer if actual electric fuel costs exceeded allowed electric fuel costs in latest rate order. + References No definition available. + Details
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