Segment Information (Details)
$ in Thousands |
3 Months Ended |
9 Months Ended |
|
Sep. 30, 2026
USD ($)
|
Sep. 30, 2025
USD ($)
|
Sep. 30, 2026
USD ($)
Segment
|
Sep. 30, 2025
USD ($)
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
$ 190,397
|
$ 175,679
|
$ 594,295
|
$ 554,101
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Income tax (provision) benefit |
|
(9,390)
|
(7,789)
|
(19,525)
|
(17,060)
|
| Equity in earnings of investment |
|
|
|
11,261
|
9,586
|
| Net Income (Loss) |
|
56,358
|
44,497
|
138,192
|
112,587
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
$ 292,222
|
255,622
|
| Number of Reportable Segments | Segment |
|
|
|
4
|
|
| Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
172,714
|
155,277
|
$ 435,474
|
410,044
|
| Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
17,469
|
20,188
|
158,333
|
143,594
|
| Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
214
|
214
|
488
|
463
|
| Transmission Investment [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| All Others [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| Operating Segments [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
190,397
|
175,679
|
594,295
|
554,101
|
| Fuel and purchased power |
|
(29,133)
|
(26,478)
|
(70,629)
|
(70,279)
|
| Purchased gas costs |
|
(461)
|
(4,865)
|
(80,569)
|
(70,142)
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Interest expense |
|
(11,295)
|
(9,412)
|
(33,669)
|
(27,716)
|
| Other segment items |
[1] |
(58,383)
|
(57,167)
|
(176,642)
|
(181,055)
|
| Income tax (provision) benefit |
|
(9,390)
|
(7,789)
|
(19,525)
|
(17,060)
|
| Equity in earnings of investment |
|
3,925
|
3,345
|
11,261
|
9,586
|
| Net Income (Loss) |
|
56,358
|
44,497
|
138,192
|
112,587
|
| Operating Segments [Member] | Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
172,719
|
155,179
|
435,461
|
409,870
|
| Fuel and purchased power |
|
(30,512)
|
(27,878)
|
(74,094)
|
(73,508)
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
(22,278)
|
(22,470)
|
(65,491)
|
(66,099)
|
| Interest expense |
|
(8,231)
|
(6,703)
|
(24,478)
|
(19,681)
|
| Other segment items |
[1] |
(58,211)
|
(56,785)
|
(171,362)
|
(170,894)
|
| Income tax (provision) benefit |
|
(5,565)
|
(5,039)
|
(3,821)
|
(3,609)
|
| Equity in earnings of investment |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
47,922
|
36,304
|
96,215
|
76,079
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
241,768
|
210,095
|
| Operating Segments [Member] | Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
22,869
|
26,581
|
174,942
|
159,017
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
(4,494)
|
(9,868)
|
(93,750)
|
(82,369)
|
| Depreciation and amortization |
|
(5,034)
|
(4,396)
|
(14,898)
|
(12,975)
|
| Interest expense |
|
(2,263)
|
(1,836)
|
(6,736)
|
(5,367)
|
| Other segment items |
[1] |
(16,247)
|
(14,439)
|
(47,224)
|
(45,550)
|
| Income tax (provision) benefit |
|
1,500
|
1,148
|
(3,164)
|
(3,278)
|
| Equity in earnings of investment |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
(3,669)
|
(2,810)
|
9,170
|
9,478
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
41,183
|
36,396
|
| Operating Segments [Member] | Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
11,987
|
11,463
|
35,255
|
33,937
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
(1,990)
|
(1,950)
|
(5,941)
|
(5,774)
|
| Interest expense |
|
(801)
|
(873)
|
(2,455)
|
(2,668)
|
| Other segment items |
[1] |
(37)
|
(30)
|
(118)
|
(97)
|
| Income tax (provision) benefit |
|
(2,495)
|
(2,345)
|
(7,284)
|
(6,918)
|
| Equity in earnings of investment |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
6,664
|
6,265
|
19,457
|
18,480
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
9,271
|
9,131
|
| Operating Segments [Member] | Transmission Investment [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
0
|
0
|
0
|
0
|
| Interest expense |
|
0
|
0
|
0
|
0
|
| Other segment items |
[1] |
0
|
0
|
0
|
0
|
| Income tax (provision) benefit |
|
(1,069)
|
(912)
|
(3,068)
|
(2,614)
|
| Equity in earnings of investment |
|
3,925
|
3,345
|
11,261
|
9,586
|
| Net Income (Loss) |
|
2,856
|
2,433
|
8,193
|
6,972
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
0
|
0
|
| Operating Segments [Member] | Total Reportable Segments |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
207,575
|
193,223
|
645,658
|
602,824
|
| Fuel and purchased power |
|
(30,512)
|
(27,878)
|
(74,094)
|
(73,508)
|
| Purchased gas costs |
|
(4,494)
|
(9,868)
|
(93,750)
|
(82,369)
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Interest expense |
|
(11,295)
|
(9,412)
|
(33,669)
|
(27,716)
|
| Other segment items |
[1] |
(74,495)
|
(71,254)
|
(218,704)
|
(216,541)
|
| Income tax (provision) benefit |
|
(7,629)
|
(7,148)
|
(17,337)
|
(16,419)
|
| Equity in earnings of investment |
|
3,925
|
3,345
|
11,261
|
9,586
|
| Net Income (Loss) |
|
53,773
|
42,192
|
133,035
|
111,009
|
| Operating Segments [Member] | All Others [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
0
|
0
|
0
|
0
|
| Interest expense |
|
0
|
0
|
0
|
0
|
| Other segment items |
[1] |
4,346
|
2,946
|
7,345
|
2,219
|
| Income tax (provision) benefit |
|
(1,761)
|
(641)
|
(2,188)
|
(641)
|
| Equity in earnings of investment |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
2,585
|
2,305
|
5,157
|
1,578
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
0
|
0
|
| Consolidation Elimination Entries [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
(17,178)
|
(17,544)
|
(51,363)
|
(48,723)
|
| Fuel and purchased power |
|
1,379
|
1,400
|
3,465
|
3,229
|
| Purchased gas costs |
|
4,033
|
5,003
|
13,181
|
12,227
|
| Depreciation and amortization |
|
0
|
0
|
0
|
0
|
| Interest expense |
|
0
|
0
|
0
|
0
|
| Other segment items |
[1] |
11,766
|
11,141
|
34,717
|
33,267
|
| Income tax (provision) benefit |
|
0
|
0
|
0
|
0
|
| Equity in earnings of investment |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
0
|
0
|
0
|
0
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
0
|
0
|
| Consolidation Elimination Entries [Member] | Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
5
|
(98)
|
(13)
|
(174)
|
| Consolidation Elimination Entries [Member] | Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
5,400
|
6,393
|
16,609
|
15,423
|
| Consolidation Elimination Entries [Member] | Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
11,773
|
11,249
|
34,767
|
33,474
|
| Consolidation Elimination Entries [Member] | Transmission Investment [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| Consolidation Elimination Entries [Member] | Total Reportable Segments |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
17,178
|
17,544
|
51,363
|
48,723
|
| Consolidation Elimination Entries [Member] | All Others [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
0
|
0
|
0
|
0
|
| MGE [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
190,397
|
175,679
|
594,295
|
554,101
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Income tax (provision) benefit |
|
(6,560)
|
(6,236)
|
(14,269)
|
(13,805)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
5,764
|
5,668
|
17,099
|
16,981
|
| Net Income (Loss) |
|
45,153
|
34,091
|
107,743
|
87,056
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
$ 292,222
|
255,622
|
| Number of Reportable Segments | Segment |
|
|
|
3
|
|
| MGE [Member] | Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
172,714
|
155,277
|
$ 435,474
|
410,044
|
| MGE [Member] | Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
17,469
|
20,188
|
158,333
|
143,594
|
| MGE [Member] | Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
214
|
214
|
488
|
463
|
| MGE [Member] | Operating Segments [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
190,397
|
175,679
|
594,295
|
554,101
|
| Fuel and purchased power |
|
(29,133)
|
(26,478)
|
(70,629)
|
(70,279)
|
| Purchased gas costs |
|
(461)
|
(4,865)
|
(80,569)
|
(70,142)
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Interest expense |
|
(11,295)
|
(9,412)
|
(33,669)
|
(27,716)
|
| Other segment items |
[2] |
(62,729)
|
(60,113)
|
(183,987)
|
(183,274)
|
| Income tax (provision) benefit |
|
(6,560)
|
(6,236)
|
(14,269)
|
(13,805)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
(5,764)
|
(5,668)
|
(17,099)
|
(16,981)
|
| Net Income (Loss) |
|
45,153
|
34,091
|
107,743
|
87,056
|
| MGE [Member] | Operating Segments [Member] | Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
172,719
|
155,179
|
435,461
|
409,870
|
| Fuel and purchased power |
|
(30,512)
|
(27,878)
|
(74,094)
|
(73,508)
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
(22,278)
|
(22,470)
|
(65,491)
|
(66,099)
|
| Interest expense |
|
(8,231)
|
(6,703)
|
(24,478)
|
(19,681)
|
| Other segment items |
[2] |
(58,211)
|
(56,785)
|
(171,362)
|
(170,894)
|
| Income tax (provision) benefit |
|
(5,565)
|
(5,039)
|
(3,821)
|
(3,609)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
47,922
|
36,304
|
96,215
|
76,079
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
241,768
|
210,095
|
| MGE [Member] | Operating Segments [Member] | Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
22,869
|
26,581
|
174,942
|
159,017
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
(4,494)
|
(9,868)
|
(93,750)
|
(82,369)
|
| Depreciation and amortization |
|
(5,034)
|
(4,396)
|
(14,898)
|
(12,975)
|
| Interest expense |
|
(2,263)
|
(1,836)
|
(6,736)
|
(5,367)
|
| Other segment items |
[2] |
(16,247)
|
(14,439)
|
(47,224)
|
(45,550)
|
| Income tax (provision) benefit |
|
1,500
|
1,148
|
(3,164)
|
(3,278)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
(3,669)
|
(2,810)
|
9,170
|
9,478
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
41,183
|
36,396
|
| MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
11,987
|
11,463
|
35,255
|
33,937
|
| Fuel and purchased power |
|
0
|
0
|
0
|
0
|
| Purchased gas costs |
|
0
|
0
|
0
|
0
|
| Depreciation and amortization |
|
(1,990)
|
(1,950)
|
(5,941)
|
(5,774)
|
| Interest expense |
|
(801)
|
(873)
|
(2,455)
|
(2,668)
|
| Other segment items |
[2] |
(37)
|
(30)
|
(118)
|
(97)
|
| Income tax (provision) benefit |
|
(2,495)
|
(2,345)
|
(7,284)
|
(6,918)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
6,664
|
6,265
|
19,457
|
18,480
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
9,271
|
9,131
|
| MGE [Member] | Operating Segments [Member] | Total Reportable Segments |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
207,575
|
193,223
|
645,658
|
602,824
|
| Fuel and purchased power |
|
(30,512)
|
(27,878)
|
(74,094)
|
(73,508)
|
| Purchased gas costs |
|
(4,494)
|
(9,868)
|
(93,750)
|
(82,369)
|
| Depreciation and amortization |
|
(29,302)
|
(28,816)
|
(86,330)
|
(84,848)
|
| Interest expense |
|
(11,295)
|
(9,412)
|
(33,669)
|
(27,716)
|
| Other segment items |
[2] |
(74,495)
|
(71,254)
|
(218,704)
|
(216,541)
|
| Income tax (provision) benefit |
|
(6,560)
|
(6,236)
|
(14,269)
|
(13,805)
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) |
|
50,917
|
39,759
|
124,842
|
104,037
|
| MGE [Member] | Consolidation Elimination Entries [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
(17,178)
|
(17,544)
|
(51,363)
|
(48,723)
|
| Fuel and purchased power |
|
1,379
|
1,400
|
3,465
|
3,229
|
| Purchased gas costs |
|
4,033
|
5,003
|
13,181
|
12,227
|
| Depreciation and amortization |
|
0
|
0
|
0
|
0
|
| Interest expense |
|
0
|
0
|
0
|
0
|
| Other segment items |
[2] |
11,766
|
11,141
|
34,717
|
33,267
|
| Income tax (provision) benefit |
|
0
|
0
|
0
|
0
|
| Net Income (Loss) Attributable to Noncontrolling Interest |
|
(5,764)
|
(5,668)
|
(17,099)
|
(16,981)
|
| Net Income (Loss) |
|
(5,764)
|
(5,668)
|
(17,099)
|
(16,981)
|
| Segment Reporting Information Assets And Capital Expenditures [Abstract] |
|
|
|
|
|
| Segment Reporting, Long-Lived Asset, Expenditure for Addition |
|
|
|
0
|
0
|
| MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
5
|
(98)
|
(13)
|
(174)
|
| MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
5,400
|
6,393
|
16,609
|
15,423
|
| MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member] |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
11,773
|
11,249
|
34,767
|
33,474
|
| MGE [Member] | Consolidation Elimination Entries [Member] | Total Reportable Segments |
|
|
|
|
|
| Segment Reporting [Line Items] |
|
|
|
|
|
| Operating revenues |
|
$ 17,178
|
$ 17,544
|
$ 51,363
|
$ 48,723
|
|
|