XML 69 R52.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Segment Information (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | $ 121,576 | $ 122,126 | $ 269,103 | $ 292,260
Depreciation and amortization |  | (11,114) | (10,995) | (22,146) | (21,844)
Other operating expenses |  | (82,250) | (87,082) | (189,214) | (214,516)
Operating income (loss) |  | 28,212 | 24,049 | 57,743 | 55,900
Other income (deductions), net |  | 2,179 | 2,446 | 4,621 | 4,551
Interest (expense) income, net |  | (4,957) | (5,008) | (9,957) | (10,099)
Income before income taxes |  | 25,434 | 21,487 | 52,407 | 50,352
Income tax (provision) benefit |  | (9,284) | (8,008) | (19,229) | (18,595)
Net Income (Loss) |  | 16,150 | 13,479 | 33,178 | 31,757
Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 100,329 | 99,481 | 193,537 | 197,721
Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 20,961 | 20,669 | 74,798 | 90,597
Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 286 | 1,976 | 768 | 3,942
Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
All Others [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
Operating Segments [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 121,576 | 122,126 | 269,103 | 292,260
Operating Segments [Member] | Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 100,896 | 99,603 | 194,560 | 197,958
Depreciation and amortization |  | (7,259) | (7,456) | (14,422) | (14,788)
Other operating expenses |  | (78,291) | (79,961) | (153,670) | (159,761)
Operating income (loss) |  | 15,346 | 12,186 | 26,468 | 23,409
Other income (deductions), net |  | 118 | 16 | 314 | 106
Interest (expense) income, net |  | (2,776) | (2,768) | (5,566) | (5,587)
Income before income taxes |  | 12,688 | 9,434 | 21,216 | 17,928
Income tax (provision) benefit |  | (4,158) | (3,164) | (6,694) | (5,547)
Net Income (Loss) |  | 8,530 | 6,270 | 14,522 | 12,381
Operating Segments [Member] | Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 27,102 | 22,960 | 86,036 | 95,613
Depreciation and amortization |  | (2,015) | (1,662) | (3,996) | (3,304)
Other operating expenses |  | (21,295) | (19,089) | (69,036) | (79,157)
Operating income (loss) |  | 3,792 | 2,209 | 13,004 | 13,152
Other income (deductions), net |  | (18) | (25) | (26) | (26)
Interest (expense) income, net |  | (799) | (790) | (1,607) | (1,594)
Income before income taxes |  | 2,975 | 1,394 | 11,371 | 11,532
Income tax (provision) benefit |  | (1,195) | (557) | (4,554) | (4,638)
Net Income (Loss) |  | 1,780 | 837 | 6,817 | 6,894
Operating Segments [Member] | Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 11,205 | 11,829 | 22,664 | 23,642
Depreciation and amortization |  | (1,828) | (1,866) | (3,704) | (3,729)
Other operating expenses |  | (35) | (36) | (82) | (86)
Operating income (loss) |  | 9,342 | 9,927 | 18,878 | 19,827
Other income (deductions), net |  | 0 | 0 | 0 | 0
Interest (expense) income, net |  | (1,449) | (1,507) | (2,912) | (3,025)
Income before income taxes |  | 7,893 | 8,420 | 15,966 | 16,802
Income tax (provision) benefit |  | (3,168) | (3,380) | (6,408) | (6,744)
Net Income (Loss) |  | 4,725 | 5,040 | 9,558 | 10,058
Operating Segments [Member] | Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
Depreciation and amortization |  | 0 | 0 | 0 | 0
Other operating expenses |  | (3) | 0 | (4) | 0
Operating income (loss) |  | (3) | 0 | (4) | 0
Other income (deductions), net |  | 1,767 | 2,290 | 4,000 | 4,171
Interest (expense) income, net |  | 0 | 0 | 0 | 0
Income before income taxes |  | 1,764 | 2,290 | 3,996 | 4,171
Income tax (provision) benefit |  | (709) | (919) | (1,606) | (1,675)
Net Income (Loss) |  | 1,055 | 1,371 | 2,390 | 2,496
Operating Segments [Member] | All Others [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
Depreciation and amortization |  | (12) | (11) | (24) | (23)
Other operating expenses |  | (253) | (262) | (579) | (465)
Operating income (loss) |  | (265) | (273) | (603) | (488)
Other income (deductions), net |  | 312 | 165 | 333 | 300
Interest (expense) income, net |  | 67 | 57 | 128 | 107
Income before income taxes |  | 114 | (51) | (142) | (81)
Income tax (provision) benefit |  | (54) | 12 | 33 | 9
Net Income (Loss) |  | 60 | (39) | (109) | (72)
Consolidation Elimination Entries [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | (17,627) | (12,266) | (34,157) | (24,953)
Depreciation and amortization |  | 0 | 0 | 0 | 0
Other operating expenses |  | 17,627 | 12,266 | 34,157 | 24,953
Operating income (loss) |  | 0 | 0 | 0 | 0
Other income (deductions), net |  | 0 | 0 | 0 | 0
Interest (expense) income, net |  | 0 | 0 | 0 | 0
Income before income taxes |  | 0 | 0 | 0 | 0
Income tax (provision) benefit |  | 0 | 0 | 0 | 0
Net Income (Loss) |  | 0 | 0 | 0 | 0
Consolidation Elimination Entries [Member] | Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 567 | 122 | 1,023 | 237
Consolidation Elimination Entries [Member] | Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 6,141 | 2,291 | 11,238 | 5,016
Consolidation Elimination Entries [Member] | Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 10,919 | 9,853 | 21,896 | 19,700
Consolidation Elimination Entries [Member] | Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
Consolidation Elimination Entries [Member] | All Others [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
MGE [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 121,589 | 122,133 | 269,132 | 292,277
Depreciation and amortization |  | (11,102) | (10,984) | (22,122) | (21,821)
Other operating expenses | [1] | (90,473) | (93,868) | (206,217) | (230,885)
Operating income (loss) | [1] | 20,014 | 17,281 | 40,793 | 39,571
Other income (deductions), net | [1] | 1,100 | 1,302 | 2,579 | 2,464
Interest (expense) income, net |  | (5,024) | (5,065) | (10,085) | (10,206)
Income tax (provision) benefit |  | (8,464) | (7,041) | (17,554) | (16,817)
Net Income Including Noncontrolling Interest |  | 16,090 | 13,518 | 33,287 | 31,829
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | (5,952) | (6,626) | (12,204) | (13,179)
Net Income (Loss) |  | 10,138 | 6,892 | 21,083 | 18,650
MGE [Member] | Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 100,336 | 99,486 | 193,550 | 197,731
MGE [Member] | Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 20,967 | 20,671 | 74,814 | 90,604
MGE [Member] | Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 286 | 1,976 | 768 | 3,942
MGE [Member] | Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
MGE [Member] | Operating Segments [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 121,589 | 122,133 | 269,132 | 292,277
MGE [Member] | Operating Segments [Member] | Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 100,896 | 99,603 | 194,560 | 197,958
Depreciation and amortization |  | (7,259) | (7,456) | (14,422) | (14,788)
Other operating expenses | [1] | (82,405) | (83,079) | (160,284) | (165,221)
Operating income (loss) | [1] | 11,232 | 9,068 | 19,854 | 17,949
Other income (deductions), net | [1] | 74 | (30) | 234 | 19
Interest (expense) income, net |  | (2,776) | (2,768) | (5,566) | (5,587)
Net Income Including Noncontrolling Interest |  | 8,530 | 6,270 | 14,522 | 12,381
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | 0 | 0 | 0 | 0
Net Income (Loss) |  | 8,530 | 6,270 | 14,522 | 12,381
MGE [Member] | Operating Segments [Member] | Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 27,102 | 22,960 | 86,036 | 95,613
Depreciation and amortization |  | (2,015) | (1,662) | (3,996) | (3,304)
Other operating expenses | [1] | (22,476) | (19,632) | (73,567) | (83,770)
Operating income (loss) | [1] | 2,611 | 1,666 | 8,473 | 8,539
Other income (deductions), net | [1] | (32) | (39) | (49) | (51)
Interest (expense) income, net |  | (799) | (790) | (1,607) | (1,594)
Net Income Including Noncontrolling Interest |  | 1,780 | 837 | 6,817 | 6,894
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | 0 | 0 | 0 | 0
Net Income (Loss) |  | 1,780 | 837 | 6,817 | 6,894
MGE [Member] | Operating Segments [Member] | Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 11,205 | 11,829 | 22,664 | 23,642
Depreciation and amortization |  | (1,828) | (1,866) | (3,704) | (3,729)
Other operating expenses | [1] | (3,203) | (3,416) | (6,490) | (6,830)
Operating income (loss) | [1] | 6,174 | 6,547 | 12,470 | 13,083
Other income (deductions), net | [1] | 0 | 0 | 0 | 0
Interest (expense) income, net |  | (1,449) | (1,507) | (2,912) | (3,025)
Net Income Including Noncontrolling Interest |  | 4,725 | 5,040 | 9,558 | 10,058
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | 0 | 0 | 0 | 0
Net Income (Loss) |  | 4,725 | 5,040 | 9,558 | 10,058
MGE [Member] | Operating Segments [Member] | Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 0 | 0 | 0 | 0
Depreciation and amortization |  | 0 | 0 | 0 | 0
Other operating expenses | [1] | (3) | 0 | (4) | 0
Operating income (loss) | [1] | (3) | 0 | (4) | 0
Other income (deductions), net | [1] | 1,058 | 1,371 | 2,394 | 2,496
Interest (expense) income, net |  | 0 | 0 | 0 | 0
Net Income Including Noncontrolling Interest |  | 1,055 | 1,371 | 2,390 | 2,496
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | 0 | 0 | 0 | 0
Net Income (Loss) |  | 1,055 | 1,371 | 2,390 | 2,496
MGE [Member] | Consolidation Elimination Entries [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | (17,614) | (12,259) | (34,128) | (24,936)
Depreciation and amortization |  | 0 | 0 | 0 | 0
Other operating expenses | [1] | 17,614 | 12,259 | 34,128 | 24,936
Operating income (loss) | [1] | 0 | 0 | 0 | 0
Other income (deductions), net | [1] | 0 | 0 | 0 | 0
Interest (expense) income, net |  | 0 | 0 | 0 | 0
Net Income Including Noncontrolling Interest |  | 0 | 0 | 0 | 0
Less Net Income Attributable to Noncontrolling Interest, net of tax |  | (5,952) | (6,626) | (12,204) | (13,179)
Net Income (Loss) |  | (5,952) | (6,626) | (12,204) | (13,179)
MGE [Member] | Consolidation Elimination Entries [Member] | Electric [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 560 | 117 | 1,010 | 227
MGE [Member] | Consolidation Elimination Entries [Member] | Gas [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 6,135 | 2,289 | 11,222 | 5,009
MGE [Member] | Consolidation Elimination Entries [Member] | Non Regulated Energy [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | 10,919 | 9,853 | 21,896 | 19,700
MGE [Member] | Consolidation Elimination Entries [Member] | Transmission Investment [Member] |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |
Operating revenues |  | $ 0 | $ 0 | $ 0 | $ 0
[1] | *Amounts are shown net of the related tax expense, consistent with the presentation on the MGE Consolidated Statement of Income.

X
- References No definition available. + Details
Name: | mgee_UtilitiesOperatingExpenseExcludingDepreciationAndAmortization
Namespace Prefix: | mgee_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)(1)(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 9 -Subparagraph (a),(b) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32639-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(h)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Income Tax Expense (or Benefit) -URI http://asc.fasb.org/extlink&oid=6515339 + Details
Name: | us-gaap_IncomeTaxExpenseBenefit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The net amount of operating interest income (expense). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.10) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
Name: | us-gaap_InterestIncomeExpenseNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The portion of profit or loss for the period, net of income taxes, which is attributable to the parent. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Net Income -URI http://asc.fasb.org/extlink&oid=51831255 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.19) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.18) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.22) -URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Other Comprehensive Income -URI http://asc.fasb.org/extlink&oid=51831270 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 19 -Article 5 Reference 9: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph 20 -Article 9 + Details
Name: | us-gaap_NetIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of Net Income (Loss) attributable to noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4J -URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591551-111686 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684 + Details
Name: | us-gaap_NetIncomeLossAttributableToNoncontrollingInterest
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.7) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_NonoperatingIncomeExpense
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The net result for the period of deducting operating expenses from operating revenues. + References No definition available. + Details
Name: | us-gaap_OperatingIncomeLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 19 -URI http://asc.fasb.org/extlink&oid=51664549&loc=SL4569616-111683 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4K -URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591552-111686 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (a),(c) -URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 55 -Paragraph 4J -URI http://asc.fasb.org/extlink&oid=35736750&loc=SL4591551-111686 + Details
Name: | us-gaap_ProfitLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The total amount of operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedAndUnregulatedOperatingRevenue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_SegmentReportingInformationLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of operating expense for depreciation and amortization of regulated operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 + Details
Name: | us-gaap_UtilitiesOperatingExpenseDepreciationAndAmortization
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mgee_ElectricMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mgee_GasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mgee_NonRegulatedEnergyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=mgee_TransmissionInvestmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementBusinessSegmentsAxis=us-gaap_CorporateAndOtherMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_OperatingSegmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ConsolidationItemsAxis=us-gaap_IntersegmentEliminationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | dei_LegalEntityAxis=us-gaap_SubsidiariesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |