Investments (Tables)

12 Months Ended

Dec. 31, 2025

Investments Disclosure [Abstract]

Equity Method and Other Investments

a.Equity Securities, Equity Method Investments, and Other Investments.

	MGE Energy
(In thousands)	2025		2024
Equity securities	$	22,591	$	23,119
Equity method investments:
ATC and ATC Holdco		102,985		92,579
Other		39		39
Total equity method investments		103,024		92,618
Other investments		2,298		2,298
Total	$	127,913	$	118,035

For the years ended December 31, 2025, 2024, and 2023, there were no material liquidated investments for MGE. For the years ended December 31, 2025, 2024, and 2023, certain investments were liquidated for MGE Energy. As a result of these liquidations, the following was received:

(In thousands)	2025		2024		2023
Cash proceeds	$	4,497	$	2,554	$	995
Gain (loss) on sale		3,263		239		(899	)

Equity Method Investments Summarized Financial Data

For the following years ended December 31, MGE Transco recorded the following:

(In thousands)	2025		2024		2023
Equity earnings from investment in ATC	$	12,682	$	12,498	$	10,515
Dividends received from ATC		10,612		8,635		8,397
Capital contributions to ATC		8,385		2,679		3,750

ATC's summarized financial data is as follows:

(In thousands)
Income statement data for the year ended December 31,	2025			2024			2023
Operating revenues	$	974,956		$	911,314		$	818,921
Operating expenses		(472,610	)		(442,359	)		(407,643	)
Other income		1,364			1,407			2,452
Interest expense, net		(167,152	)		(139,204	)		(134,107	)
Earnings before members' income taxes	$	336,558		$	331,158		$	279,623
Balance sheet data as of December 31,	2025			2024
Current assets	$	137,522		$	126,628
Noncurrent assets		7,590,778			6,792,600
Total assets	$	7,728,300		$	6,919,228
Current liabilities	$	839,789		$	482,440
Long-term debt		3,156,253			3,083,409
Other noncurrent liabilities		638,916			544,973
Members' equity		3,093,342			2,808,406
Total members' equity and liabilities	$	7,728,300		$	6,919,228