XML 106 R40.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Joint Plant Ownership (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2019
Columbia Units [Member] |
Jointly Owned Utility Plant Interests [Line Items] |
Schedule of Joint Plant Ownership | MGE's interest in Columbia's gross utility plant in service, and the related accumulated depreciation reserves as of December 31 were as follows:
| (In thousands) |  | 2019 |  | 2018 |
| Utility plant | $ | 291,997 | $ | 292,157 |
| Accumulated depreciation |  | (105,778) |  | (94,766) |
| Property, plant, and equipment, net |  | 186,219 |  | 197,391 |
| Construction work in progress |  | 1,777 |  | 2,021 |
| Total property, plant, and equipment | $ | 187,996 | $ | 199,412 |
Elm Road Units [Member] |
Jointly Owned Utility Plant Interests [Line Items] |
Schedule of Joint Plant Ownership | MGE Power Elm Road's interest in the portion of the Elm Road Units in-service and the related accumulated depreciation reserves as of December 31 were as follows:
| (In thousands) |  | 2019 |  | 2018 |
| Nonregulated plant | $ | 207,834 | $ | 207,361 |
| Accumulated depreciation |  | (37,071) |  | (33,897) |
| Property, plant, and equipment, net |  | 170,763 |  | 173,464 |
| Construction work in progress |  | 468 |  | 530 |
| Total property, plant, and equipment | $ | 171,231 | $ | 173,994 |
Forward Wind [Member] |
Jointly Owned Utility Plant Interests [Line Items] |
Schedule of Joint Plant Ownership | MGE's interest in the portion of Forward Wind's utility plant in service and the related accumulated depreciation reserves as of December 31 were as follows:
| (In thousands) |  | 2019 |  | 2018 |
| Utility plant | $ | 34,054 | $ | 33,929 |
| Accumulated depreciation |  | (13,413) |  | (12,530) |
| Property, plant, and equipment, net |  | 20,641 |  | 21,399 |
| Construction work in progress |  | 45 |  | 67 |
| Total property, plant, and equipment | $ | 20,686 | $ | 21,466 |
West Campus [Member] |
Jointly Owned Utility Plant Interests [Line Items] |
Schedule of Joint Plant Ownership | MGE Power West Campus' interest in WCCF and the related accumulated depreciation reserves as of December 31 were as follows:
| (In thousands) |  | 2019 |  | 2018 |
| Nonregulated plant | $ | 113,259 | $ | 113,328 |
| Accumulated depreciation |  | (33,786) |  | (32,055) |
| Property, plant, and equipment, net |  | 79,473 |  | 81,273 |
| Construction work in progress |  | 309 |  | 478 |
| Total property, plant, and equipment | $ | 79,782 | $ | 81,751 |

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_JointlyOwnedUtilityPlantInterestsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI http://asc.fasb.org/extlink&oid=115995737&loc=d3e659983-123033 + Details
Name: | us-gaap_ScheduleOfJointlyOwnedUtilityPlantsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=mgee_ColumbiaUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=mgee_ElmRoadUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=mgee_ForwardWindMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=mgee_WestCampusMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |