Summary of Significant Accounting Policies (Details-1) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Trade Receivables, Allowance for Doubtful Accounts, and Concentration Risk
Late payment charge on upaid receivables		1.00%
Accounts receivable, allowance for credit loss, writeoff		$ 4,000	$ 3,600
Accounts receivable, allowance for credit loss, period increase		4,900	3,300
Accounts receivable, allowance for credit loss		9,000	8,100
Allowance for Funds Used During Construction
AFUDC - borrowed funds		2,200	2,000	$ 1,100
AFUDC - equity funds		5,700	5,800	3,000
Capitalized Software Costs
Capitalized software		67,500	77,200
Capitalized software - accumulated amortization		74,400	63,900
Capitalized software - amortization		10,500	10,400	10,800
Capitalized Software Hosting Agreement Costs
Capitalized software hosting agreement		8,500	10,700
Capitalized software hosting agreement - accumulated amortization		14,600	11,400
Capitalized software hosting agreement - amortization expense		3,200	2,900	3,100
Tangible Asset Impairment Charges [Abstract]
Impairment, Long-Lived Asset, Held-for-Use		$ 0	0	0
Excise taxes
License fee tax rate, electric, retail sales		3.19%
License fee tax rate, electric, resale by purchaser		1.59%
License fee tax rate, natural gas		0.97%
License fee tax expense		$ 17,000	$ 16,500	$ 14,700
Minimum [Member]
Capitalized Software Hosting Agreement Costs
Capitalized software hosting agreement, useful life		3 years
Minimum [Member] | Capitalized Software [Member]
Property, Plant, and Equiptment
Property, plant, and equipment, useful life		3 years
Maximum [Member]
Capitalized Software Hosting Agreement Costs
Capitalized software hosting agreement, useful life		13 years
Maximum [Member] | Capitalized Software [Member]
Property, Plant, and Equiptment
Property, plant, and equipment, useful life		15 years
PSCW [Member]
Allowance for Funds Used During Construction
Authorized AFUDC rate		50.00%	50.00%	50.00%
Rate at which AFUDC was capitalized		7.73%	7.11%	7.11%
Authorized AFUDC rate - Signficiant projects (100%)		100.00%	100.00%	100.00%
Electric [Member]
Property, Plant, and Equiptment
Composite straight-line depreciation rates	[1]	3.80%	3.80%	3.20%
Gas [Member]
Property, Plant, and Equiptment
Composite straight-line depreciation rates		2.10%	2.10%	2.10%
Non Regulated Energy [Member]
Property, Plant, and Equiptment
Composite straight-line depreciation rates		2.30%	2.30%	2.30%
MGE Power Elm Road [Member]
Principles of Consolidation
Ownership percentage by parent		100.00%
MGE Power West Campus [Member]
Principles of Consolidation
Ownership percentage by parent		100.00%

[1] In the 2023 limited reopener, the PSCW approved new depreciation rates for Columbia effective January 1, 2023