v3.26.1
Segment Information (Details)
$ in Thousands
 3 Months Ended
Mar. 31, 2026
USD ($)
Segment
Mar. 31, 2025
USD ($)
Segment Reporting Information [Line Items]    
Operating revenues $ 242,703 $ 218,970
Depreciation and amortization (28,089) (27,678)
Income tax (provision) benefit (5,856) (6,296)
Equity in earnings of investment 3,541 3,181
Net Income (Loss) 48,481 41,592
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets $ 101,140 47,653
Number of Reportable Segments | Segment 4  
Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues $ 131,380 125,454
Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 111,263 93,481
Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 60 35
Transmission Investment [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
All Others [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
Operating Segments [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 242,703 218,970
Fuel and purchased power (22,776) (21,947)
Purchased gas costs (70,823) (53,964)
Depreciation and amortization (28,089) (27,678)
Interest expense (11,138) (9,162)
Other segment items [1] (59,081) (61,512)
Income tax (provision) benefit (5,856) (6,296)
Equity in earnings of investment 3,541 3,181
Net Income (Loss) 48,481 41,592
Operating Segments [Member] | Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 131,372 125,406
Fuel and purchased power (24,073) (23,106)
Purchased gas costs 0 0
Depreciation and amortization (21,254) (21,535)
Interest expense (8,079) (6,493)
Other segment items [1] (55,274) (55,979)
Income tax (provision) benefit 2,981 1,902
Equity in earnings of investment 0 0
Net Income (Loss) 25,673 20,195
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 84,901 31,322
Operating Segments [Member] | Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 120,277 99,953
Fuel and purchased power 0 0
Purchased gas costs (78,554) (59,290)
Depreciation and amortization (4,865) (4,232)
Interest expense (2,223) (1,763)
Other segment items [1] (15,605) (16,096)
Income tax (provision) benefit (5,263) (4,987)
Equity in earnings of investment 0 0
Net Income (Loss) 13,767 13,585
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 12,191 14,017
Operating Segments [Member] | Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 11,478 11,139
Fuel and purchased power 0 0
Purchased gas costs 0 0
Depreciation and amortization (1,970) (1,911)
Interest expense (836) (906)
Other segment items [1] (51) (44)
Income tax (provision) benefit (2,348) (2,255)
Equity in earnings of investment 0 0
Net Income (Loss) 6,273 6,023
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 4,048 2,314
Operating Segments [Member] | Transmission Investment [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
Fuel and purchased power 0 0
Purchased gas costs 0 0
Depreciation and amortization 0 0
Interest expense 0 0
Other segment items [1] 0 0
Income tax (provision) benefit (965) (867)
Equity in earnings of investment 3,541 3,181
Net Income (Loss) 2,576 2,314
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 0 0
Operating Segments [Member] | Total Reportable Segments    
Segment Reporting Information [Line Items]    
Operating revenues 263,127 236,498
Fuel and purchased power (24,073) (23,106)
Purchased gas costs (78,554) (59,290)
Depreciation and amortization (28,089) (27,678)
Interest expense (11,138) (9,162)
Other segment items [1] (70,930) (72,119)
Income tax (provision) benefit (5,595) (6,207)
Equity in earnings of investment 3,541 3,181
Net Income (Loss) 48,289 42,117
Operating Segments [Member] | All Others [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
Fuel and purchased power 0 0
Purchased gas costs 0 0
Depreciation and amortization 0 0
Interest expense 0 0
Other segment items [1] 453 (436)
Income tax (provision) benefit (261) (89)
Equity in earnings of investment 0 0
Net Income (Loss) 192 (525)
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 0 0
Consolidation Elimination Entries [Member]    
Segment Reporting Information [Line Items]    
Operating revenues (20,424) (17,528)
Fuel and purchased power 1,297 1,159
Purchased gas costs 7,731 5,326
Depreciation and amortization 0 0
Interest expense 0 0
Other segment items [1] 11,396 11,043
Income tax (provision) benefit 0 0
Equity in earnings of investment 0 0
Net Income (Loss) 0 0
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 0 0
Consolidation Elimination Entries [Member] | Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues (8) (48)
Consolidation Elimination Entries [Member] | Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 9,014 6,472
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 11,418 11,104
Consolidation Elimination Entries [Member] | Transmission Investment [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
Consolidation Elimination Entries [Member] | Total Reportable Segments    
Segment Reporting Information [Line Items]    
Operating revenues 20,424 17,528
Consolidation Elimination Entries [Member] | All Others [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 0 0
MGE [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 242,703 218,970
Depreciation and amortization (28,089) (27,678)
Income tax (provision) benefit (4,630) (5,340)
Net Income (Loss) Attributable to Noncontrolling Interest 5,606 5,599
Net Income (Loss) 40,107 34,204
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets $ 101,140 47,653
Number of Reportable Segments | Segment 3  
MGE [Member] | Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues $ 131,380 125,454
MGE [Member] | Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 111,263 93,481
MGE [Member] | Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 60 35
MGE [Member] | Operating Segments [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 242,703 218,970
Fuel and purchased power (22,776) (21,947)
Purchased gas costs (70,823) (53,964)
Depreciation and amortization (28,089) (27,678)
Interest expense (11,138) (9,162)
Other segment items [2] (59,534) (61,076)
Income tax (provision) benefit (4,630) (5,340)
Net Income (Loss) Attributable to Noncontrolling Interest (5,606) (5,599)
Net Income (Loss) 40,107 34,204
MGE [Member] | Operating Segments [Member] | Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 131,372 125,406
Fuel and purchased power (24,073) (23,106)
Purchased gas costs 0 0
Depreciation and amortization (21,254) (21,535)
Interest expense (8,079) (6,493)
Other segment items [2] (55,274) (55,979)
Income tax (provision) benefit 2,981 1,902
Net Income (Loss) Attributable to Noncontrolling Interest 0 0
Net Income (Loss) 25,673 20,195
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 84,901 31,322
MGE [Member] | Operating Segments [Member] | Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 120,277 99,953
Fuel and purchased power 0 0
Purchased gas costs (78,554) (59,290)
Depreciation and amortization (4,865) (4,232)
Interest expense (2,223) (1,763)
Other segment items [2] (15,605) (16,096)
Income tax (provision) benefit (5,263) (4,987)
Net Income (Loss) Attributable to Noncontrolling Interest 0 0
Net Income (Loss) 13,767 13,585
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 12,191 14,017
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 11,478 11,139
Fuel and purchased power 0 0
Purchased gas costs 0 0
Depreciation and amortization (1,970) (1,911)
Interest expense (836) (906)
Other segment items [2] (51) (44)
Income tax (provision) benefit (2,348) (2,255)
Net Income (Loss) Attributable to Noncontrolling Interest 0 0
Net Income (Loss) 6,273 6,023
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 4,048 2,314
MGE [Member] | Operating Segments [Member] | Total Reportable Segments    
Segment Reporting Information [Line Items]    
Operating revenues 263,127 236,498
Fuel and purchased power (24,073) (23,106)
Purchased gas costs (78,554) (59,290)
Depreciation and amortization (28,089) (27,678)
Interest expense (11,138) (9,162)
Other segment items [2] (70,930) (72,119)
Income tax (provision) benefit (4,630) (5,340)
Net Income (Loss) Attributable to Noncontrolling Interest 0 0
Net Income (Loss) 45,713 39,803
MGE [Member] | Consolidation Elimination Entries [Member]    
Segment Reporting Information [Line Items]    
Operating revenues (20,424) (17,528)
Fuel and purchased power 1,297 1,159
Purchased gas costs 7,731 5,326
Depreciation and amortization 0 0
Interest expense 0 0
Other segment items [2] 11,396 11,043
Income tax (provision) benefit 0 0
Net Income (Loss) Attributable to Noncontrolling Interest (5,606) (5,599)
Net Income (Loss) (5,606) (5,599)
Segment Reporting Information Assets And Capital Expenditures [Abstract]    
Segment, Expenditure, Addition to Long-Lived Assets 0 0
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member]    
Segment Reporting Information [Line Items]    
Operating revenues (8) (48)
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 9,014 6,472
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member]    
Segment Reporting Information [Line Items]    
Operating revenues 11,418 11,104
MGE [Member] | Consolidation Elimination Entries [Member] | Total Reportable Segments    
Segment Reporting Information [Line Items]    
Operating revenues $ 20,424 $ 17,528
[1] Other segment items include AFUDC Income, Other Income, Net, Other Operations and Maintenance, Other General Taxes, and Interest Revenue.
[2] Other segment items include AFUDC Income, Other Income, Net, Other Operations and Maintenance, Other General Taxes, and Interest Revenue.