Summary of Significant Accounting Policies (Details-2) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Supplemental Cash Flow Information [Abstract]
Interest paid		$ 35,755	$ 34,306	$ 29,526
US Federal	[1]	(3,970)	(16,238)	4,000
Accrued capital expenditures	[2]	55,283	22,734	17,247
Cash, Cash Equivalents, And Restricted Cash [Abstract]
Cash and cash equivalents		5,666	21,302
Restricted cash		952	1,113
Receivable - margin account		2,118	2,081
Cash, cash equivalents, and restricted cash		8,736	24,496	15,026	$ 17,968
Indemnification Agreement [Member] | Renewable Tax Credits Transferred [Member]
Effects of The Inflation Reduction Act [Abstract]
Guarantor Obligations, Liquidation Proceeds, Monetary Amount		10,900	18,500
Wisconsin
Supplemental Cash Flow Information [Abstract]
US State and Local		10,250	3,100	5,800
US State and Local - Other
Supplemental Cash Flow Information [Abstract]
US State and Local		66	36	0
MGE [Member]
Supplemental Cash Flow Information [Abstract]
Interest paid	[3]	35,755	34,306	29,526
US Federal	[1]	(5,750)	(18,658)	3,450
Accrued capital expenditures	[2],[3]	55,283	22,734	17,247
Cash, Cash Equivalents, And Restricted Cash [Abstract]
Cash and cash equivalents		2,248	16,865
Restricted cash		952	1,113
Receivable - margin account		2,118	2,081
Cash, cash equivalents, and restricted cash		5,318	20,059	6,705	$ 10,500
MGE [Member] | Wisconsin
Supplemental Cash Flow Information [Abstract]
US State and Local		9,650	2,450	5,990
MGE [Member] | US State and Local - Other
Supplemental Cash Flow Information [Abstract]
US State and Local		$ 0	$ 0	$ 0

[1] During the years ended December 31, 2025 and December 31, 2024, federal tax payments and receipts included proceeds from the transfer of PTCs under Internal Revenue Code Section 6418. Cash received for income taxes in 2025 includes $10.9 million related to PTCs generated in 2025 that were sold to a third party. Cash received for income taxes in 2024 includes $18.5 million related to PTCs generated in 2024 and 2023 that were sold to a third party.

[2] Includes a $2.0 million unsecured promissory note, for an acquisition of land, issued to the seller, with all principal and interest paid in January 2026.

[3] MGE Energy files a consolidated federal income tax return with its subsidiaries. While taxes are filed on a consolidated basis, MGE calculates its respective share of tax liability and makes intercompany tax payments to or from its parent company.