MGE Energy Inc Consolidated Statements of Common Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]
Beginning balance, shares at Dec. 31, 2023		36,163,000
Beginning balance, value at Dec. 31, 2023	$ 1,140,073	$ 36,163	$ 396,750	$ 707,160	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	33,814			33,814
Common stock dividends declared	(15,460)			(15,460)
Equity-based compensation plans and other - Shares		13,000
Issuance of common stock, net	0
Equity-based compensation plans and other	356	$ 13	343
Ending balance, shares at Mar. 31, 2024		36,176,000
Ending balance, value at Mar. 31, 2024	1,158,783	$ 36,176	397,093	725,514	0
Beginning balance, shares at Dec. 31, 2024		36,490,000
Beginning balance, value at Dec. 31, 2024	1,230,138	$ 36,490	429,515	764,133	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	41,592			41,592
Common stock dividends declared	$ (16,428)			(16,428)
Stock Issued During Period, Shares, Dividend Reinvestment Plan	35,774	36,000
Stock Issued During Period, Value, Dividend Reinvestment Plan	$ 3,279	$ 36	3,243
Equity-based compensation plans and other - Shares		11,000
Issuance of common stock, net	3,279
Equity-based compensation plans and other	332	$ 11	321
Ending balance, shares at Mar. 31, 2025		36,537,000
Ending balance, value at Mar. 31, 2025	$ 1,258,913	$ 36,537	$ 433,079	$ 789,297	$ 0