Pension Plans and Other Postretirement Benefits (Details-4) - Concentration		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024
Pension Benefits [Member] | Plan Assets [Member] | Product Concentration Risk [Member]
Concentration of Credit Risk [Abstract]
Concentration Risk, Percentage		10.00%
Concentration risk, number of significant concentrations		0
Pension Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation	[1],[2]	45.00%
Actual Plan Asset Allocation	[1]	48.00%	56.00%
Pension Benefits [Member] | United States Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		32.00%
Pension Benefits [Member] | Non-United States Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		13.00%
Pension Benefits [Member] | Fixed Income Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation	[2]	50.00%
Actual Plan Asset Allocation		47.00%	38.00%
Pension Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation	[2]	5.00%
Actual Plan Asset Allocation		5.00%	6.00%
Postretirement Benefits [Member] | Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation	[3]	63.00%
Actual Plan Asset Allocation	[3]	65.00%	66.00%
Postretirement Benefits [Member] | United States Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		45.50%
Postretirement Benefits [Member] | Non-United States Equity Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		17.50%
Postretirement Benefits [Member] | Fixed Income Securities [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		30.00%
Actual Plan Asset Allocation		29.00%	28.00%
Postretirement Benefits [Member] | Real Estate [Member]
Defined Benefit Plan, Information about Plan Assets [Abstract]
Target Plan Asset Allocation		7.00%
Actual Plan Asset Allocation		6.00%	6.00%

[1] Target allocations for equity securities are broken out as follows: 32% United States equity and 13% non-United States equity.

[2] The target allocation for MGE's pension plans were approved to be rebalanced in December 2025. The trades happened in two steps, the first in December 2025 and the second in January 2026.

[3] Target allocations for equity securities are broken out as follows: 45.5% United States equity and 17.5% non-United States equity.