Pay vs Performance Disclosure - USD ($)

12 Months Ended

Dec. 31, 2022

Dec. 31, 2021

Dec. 31, 2020

Pay vs Performance Disclosure [Table]

Pay vs Performance [Table Text Block]

Pay Versus Performance
					Value of Initial Fixed $100 Investment Based on:			Company Selected Measure
Year (a)	Summary Compensation Table Total for PEO ($)(1) (b)	Compensation Actually Paid to PEO ($)(2)(3) (c)	Average Summary Compensation Table Total for Non-PEO NEOs ($)(4) (d)	Average Compensation Actually Paid to Non-PEO NEOs ($)(2)(4)(5) (e)	Total Shareholder Return ($) (f)	Peer Group Total Shareholder Return ($)(6) (g)	Net Income ($) (h)	Earnings Per Share - Basic and Diluted ($) (i)
2022	1,678,867	1,590,003	797,155	731,318	95	117	110,882,000	3.07
2021	2,628,028	2,189,827	863,501	766,775	109	116	105,761,000	2.92
2020	2,711,113	1,522,389	1,589,557	709,072	91	99	92,418,000	2.60

(1)Reflects amounts reported in the "Summary Compensation Table" for J. Keebler (PEO).

(2)Compensation Actually Paid (CAP) includes adjustments in accordance with the SEC methodology to the total executive compensation reported from the summary compensation table. The adjustments include a deduction for actuarial present value of accumulated benefit of all defined benefit and actuarial pension plans reported in the summary compensation table; addition of actuarially determined service costs for services rendered by the executive during the covered fiscal period, deduction of grant date fair value of equity award amounts reported in the summary compensation table; and addition or subtraction of the change in fair value of the equity awards unvested and vested during the fiscal period. Compensation "actually paid" is prescribed by the rules of the disclosure and does not represent the compensation actually received by the table participants on a cash basis for any time period shown above.

(3)To calculate CAP for the PEO, the following adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:

Year	Deduction for Actuarial Pension Present Value	Addition for Service Cost for Pension	Deduction Grant Date Fair Value of Awards Granted in FY	Addition of Fair Value of Equity Awards Granted in FY	Change in Fair Value of Prior Years’ Unvested Equity Awards	Change in Fair Value of Prior Years’ Awards Vested in FY	Total Adjustment to CAP
2022	—	196,419	(504,032)	477,751	(192,116)	(66,886)	(88,864)
2021	(1,005,511)	173,740	(494,528)	645,344	192,223	50,531	(438,201)
2020	(1,213,448)	122,838	(420,052)	448,918	(113,636)	(13,344)	(1,188,724)

(4)For fiscal years 2020 through 2022, J. Bushek, L. Hobbie, C.A. Renlund, and T. Johnson are included as other named executive officers. For fiscal year 2021 D. Peterson and for fiscal year 2020 J. Newman were also included as other named executive officers.

(5)To calculate CAP for the average named executive officers, the following average adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:

Year	Deduction for Actuarial Pension Present Value	Addition for Service Cost for Pension	Deduction Grant Date Fair Value of Awards Granted in FY	Addition of Fair Value of Equity Awards Granted in FY	Change in Fair Value of Prior Years’ Unvested Equity Awards	Change in Fair Value of Prior Years’ Awards Vested in FY	Total Adjustment to CAP
2022	—	17,142	(156,186)	148,042	(55,919)	(18,916)	(65,837)
2021	(245,375)	44,404	(140,180)	182,931	48,273	13,221	(96,726)
2020	(898,791)	56,167	(133,792)	142,986	(35,715)	(11,340)	(880,485)

(6)Peer Group Total Shareholder Return of the Edison Electric Institute (EEI) Index companies.

Named Executive Officers, Footnote [Text Block]

For fiscal years 2020 through 2022, J. Bushek, L. Hobbie, C.A. Renlund, and T. Johnson are included as other named executive officers. For fiscal year 2021 D. Peterson and for fiscal year 2020 J. Newman were also included as other named executive officers

Peer Group Issuers, Footnote [Text Block]

Peer Group Total Shareholder Return of the Edison Electric Institute (EEI) Index companies

PEO Total Compensation Amount

^[1]

$ 1,678,867

$ 2,628,028

$ 2,711,113

PEO Actually Paid Compensation Amount

^[2],[3]

$ 1,590,003

2,189,827

1,522,389

Adjustment To PEO Compensation, Footnote [Text Block]

calculate CAP for the PEO, the following adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:

Year	Deduction for Actuarial Pension Present Value	Addition for Service Cost for Pension	Deduction Grant Date Fair Value of Awards Granted in FY	Addition of Fair Value of Equity Awards Granted in FY	Change in Fair Value of Prior Years’ Unvested Equity Awards	Change in Fair Value of Prior Years’ Awards Vested in FY	Total Adjustment to CAP
2022	—	196,419	(504,032)	477,751	(192,116)	(66,886)	(88,864)
2021	(1,005,511)	173,740	(494,528)	645,344	192,223	50,531	(438,201)
2020	(1,213,448)	122,838	(420,052)	448,918	(113,636)	(13,344)	(1,188,724)

Non-PEO NEO Average Total Compensation Amount

^[4]

$ 797,155

863,501

1,589,557

Non-PEO NEO Average Compensation Actually Paid Amount

^[2],[4],[5]

$ 731,318

766,775

709,072

Adjustment to Non-PEO NEO Compensation Footnote [Text Block]

calculate CAP for the average named executive officers, the following average adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:

Year	Deduction for Actuarial Pension Present Value	Addition for Service Cost for Pension	Deduction Grant Date Fair Value of Awards Granted in FY	Addition of Fair Value of Equity Awards Granted in FY	Change in Fair Value of Prior Years’ Unvested Equity Awards	Change in Fair Value of Prior Years’ Awards Vested in FY	Total Adjustment to CAP
2022	—	17,142	(156,186)	148,042	(55,919)	(18,916)	(65,837)
2021	(245,375)	44,404	(140,180)	182,931	48,273	13,221	(96,726)
2020	(898,791)	56,167	(133,792)	142,986	(35,715)	(11,340)	(880,485)

Compensation Actually Paid vs. Total Shareholder Return [Text Block]

The chart below illustrates the relationship of executive compensation actually paid and MGE Energy total shareholder return (TSR). Also included is the relationship of MGE Energy TSR and peer group TSR.

 

Compensation Actually Paid vs. Net Income [Text Block]

The chart below illustrates the relationship of executive compensation actually paid and Net Income.

 

Compensation Actually Paid vs. Company Selected Measure [Text Block]

The chart below illustrates the relationship of executive compensation actually paid and Earnings Per Share (EPS).

 

Total Shareholder Return Vs Peer Group [Text Block]

The chart below illustrates the relationship of executive compensation actually paid and MGE Energy total shareholder return (TSR). Also included is the relationship of MGE Energy TSR and peer group TSR.

 

Tabular List [Table Text Block]

The following table identifies the financial and non-financial most important performance measures used by our Committee to link compensation actually paid to our named executive officers to company performance. See further discussion in the Compensation Discussion and Analysis for description of metrics and impact to executive compensation

Performance Measures

Earnings Per Share

Return on Equity

Relative Total Shareholder Return

Customer Satisfaction Rating

Service Reliability

Total Shareholder Return Amount

$ 95

109

91

Peer Group Total Shareholder Return Amount

^[6]

117

116

99

Net Income (Loss)

$ 110,882,000

$ 105,761,000

$ 92,418,000

Company Selected Measure Amount

3.07

2.92

2.60

PEO Name

J. Keebler (PEO)

Measure [Axis]: 1

Pay vs Performance Disclosure [Table]

Measure Name

Earnings Per Share

Measure [Axis]: 2

Pay vs Performance Disclosure [Table]

Measure Name

Return on Equity

Measure [Axis]: 3

Pay vs Performance Disclosure [Table]

Measure Name

Relative Total Shareholder Return

Measure [Axis]: 4

Pay vs Performance Disclosure [Table]

Measure Name

Customer Satisfaction Rating

Measure [Axis]: 5

Pay vs Performance Disclosure [Table]

Measure Name

Service Reliability

PEO [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

$ (88,864)

$ (438,201)

$ (1,188,724)

PEO [Member] | Deduction for Actuarial Pension Present Value [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

0

(1,005,511)

(1,213,448)

PEO [Member] | Addition for Service Cost for Pension [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

196,419

173,740

122,838

PEO [Member] | Deduction Grant Date Fair Value of Awards Granted in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(504,032)

(494,528)

(420,052)

PEO [Member] | Addition of Fair Value of Equity Awards Granted in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

477,751

645,344

448,918

PEO [Member] | Change in Fair Value of Prior Years Unvested Equity Awards [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(192,116)

192,223

(113,636)

PEO [Member] | Change in Fair Value of Prior Years Awards Vested in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(66,886)

50,531

(13,344)

Non-PEO NEO [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(65,837)

(96,726)

(880,485)

Non-PEO NEO [Member] | Deduction for Actuarial Pension Present Value [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

0

(245,375)

(898,791)

Non-PEO NEO [Member] | Addition for Service Cost for Pension [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

17,142

44,404

56,167

Non-PEO NEO [Member] | Deduction Grant Date Fair Value of Awards Granted in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(156,186)

(140,180)

(133,792)

Non-PEO NEO [Member] | Addition of Fair Value of Equity Awards Granted in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

148,042

182,931

142,986

Non-PEO NEO [Member] | Change in Fair Value of Prior Years Unvested Equity Awards [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

(55,919)

48,273

(35,715)

Non-PEO NEO [Member] | Change in Fair Value of Prior Years Awards Vested in FY [Member]

Pay vs Performance Disclosure [Table]

Adjustment to Compensation Amount

$ (18,916)

$ 13,221

$ (11,340)

[1] Reflects amounts reported in the "Summary Compensation Table" for J. Keebler (PEO).

[2] Compensation Actually Paid (CAP) includes adjustments in accordance with the SEC methodology to the total executive compensation reported from the summary compensation table. The adjustments include a deduction for actuarial present value of accumulated benefit of all defined benefit and actuarial pension plans reported in the summary compensation table; addition of actuarially determined service costs for services rendered by the executive during the covered fiscal period, deduction of grant date fair value of equity award amounts reported in the summary compensation table; and addition or subtraction of the change in fair value of the equity awards unvested and vested during the fiscal period. Compensation "actually paid" is prescribed by the rules of the disclosure and does not represent the compensation actually received by the table participants on a cash basis for any time period shown above.

[3] To calculate CAP for the PEO, the following adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:   Year Deduction for Actuarial Pension Present Value Addition for Service Cost for Pension Deduction Grant Date Fair Value of Awards Granted in FY Addition of Fair Value of Equity Awards Granted in FY Change in Fair Value of Prior Years’ Unvested Equity Awards Change in Fair Value of Prior Years’ Awards Vested in FY Total Adjustment to CAP 2022 — 196,419 (504,032) 477,751 (192,116) (66,886) (88,864) 2021 (1,005,511) 173,740 (494,528) 645,344 192,223 50,531 (438,201) 2020 (1,213,448) 122,838 (420,052) 448,918 (113,636) (13,344) (1,188,724)

[4] For fiscal years 2020 through 2022, J. Bushek, L. Hobbie, C.A. Renlund, and T. Johnson are included as other named executive officers. For fiscal year 2021 D. Peterson and for fiscal year 2020 J. Newman were also included as other named executive officers.

[5] To calculate CAP for the average named executive officers, the following average adjustments were made to Summary Compensation Table total compensation, calculated in accordance with the SEC methodology for determining CAP for each year shown:   Year Deduction for Actuarial Pension Present Value Addition for Service Cost for Pension Deduction Grant Date Fair Value of Awards Granted in FY Addition of Fair Value of Equity Awards Granted in FY Change in Fair Value of Prior Years’ Unvested Equity Awards Change in Fair Value of Prior Years’ Awards Vested in FY Total Adjustment to CAP 2022 — 17,142 (156,186) 148,042 (55,919) (18,916) (65,837) 2021 (245,375) 44,404 (140,180) 182,931 48,273 13,221 (96,726) 2020 (898,791) 56,167 (133,792) 142,986 (35,715) (11,340) (880,485)

[6] Peer Group Total Shareholder Return of the Edison Electric Institute (EEI) Index companies.