Taxes (Details) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
|
| Effective Income Tax Rate Reconciliation, Percent [Abstract] | ||||
| Effective income tax rate | 14.30% | 14.90% | 12.40% | 13.20% |
| MGE [Member] | ||||
| Effective Income Tax Rate Reconciliation, Percent [Abstract] | ||||
| Effective income tax rate | 11.40% | 13.60% | 10.30% | 11.70% |
| Indemnification Agreement [Member] | Renewable Tax Credits Transferred [Member] | ||||
| Effects of The Inflation Reduction Act [Abstract] | ||||
| Guarantor Obligations, Liquidation Proceeds, Monetary Amount | $ 12.2 | |||