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v3.19.3.a.u2

Property, Plant, and Equipment (Details) | 12 Months Ended
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Dec. 31, 2019 USD ($) Turbines MW | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, net |  | $ 1,530,199,000 | $ 1,369,766,000 |
Construction work in progress |  | 112,484,000 | 139,671,000 |
Total property, plant, and equipment |  | 1,642,683,000 | 1,509,437,000 |
Assets Held For Sale |  |  |  |
Assets held for sale |  | 0 | 3,080,000 |
Allowance for Funds Used During Construction |  |  |  |
AFUDC equity recognized |  | $ 2,300,000 | $ 3,300,000 | $ 1,200,000
PSCW [Member] |  |  |  |
Allowance for Funds Used During Construction |  |  |  |
Authorized AFUDC rate |  | 50.00% | 50.00% | 50.00%
Authorized AFUDC rate - Signficiant projects (100%) |  | 100.00% | 100.00% | 100.00%
Saratoga Wind [Member] |  |  |  |
Saratoga Wind [Abstract] |  |  |  |
Saratoga Megawatts | MW |  | 66 |  |
Saratoga Turbines | Turbines |  | 33 |  |
Saratoga Wind Project Costs |  | $ 107,900,000 |  |
Allowance for Funds Used During Construction |  |  |  |
AFUDC equity recognized |  | $ 4,100,000 |  |
Saratoga Wind [Member] | PSCW [Member] |  |  |  |
Allowance for Funds Used During Construction |  |  |  |
Authorized AFUDC rate - Signficiant projects (100%) |  | 100.00% |  |
First Mortgage Bonds [Member] | 7.70%, 2028 Series |  |  |  |
Plant related debt items |  |  |  |
Long-term debt, gross | [1] | $ 1,200,000 | $ 1,200,000 |
Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 1,952,807,000 | 1,753,002,000 |
Less: Accumulated depreciation and amortization | [2] | 674,251,000 | 639,486,000 |
In-service utility plant, net |  | 1,278,556,000 | 1,113,516,000 |
Construction work in progress | [2],[3],[4] | 111,707,000 | 138,663,000 |
Electric [Member] | Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross | [2],[4] | 1,480,684,000 | 1,310,421,000 |
Gas [Member] | Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 472,123,000 | 442,581,000 |
Non Regulated Energy [Member] | Non-regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 323,266,000 | 322,855,000 |
Less: Accumulated depreciation and amortization |  | 71,623,000 | 66,605,000 |
In-service utility plant, net |  | 251,643,000 | 256,250,000 |
Construction work in progress |  | 777,000 | 1,008,000 |
MGE [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, net |  | 1,530,227,000 | 1,369,795,000 |
Construction work in progress |  | 112,484,000 | 139,671,000 |
Total property, plant, and equipment |  | 1,642,711,000 | 1,509,466,000 |
Assets Held For Sale |  |  |  |
Assets held for sale |  | 0 | 3,080,000 |
MGE [Member] | Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 1,952,835,000 | 1,753,031,000 |
Less: Accumulated depreciation and amortization | [2] | 674,251,000 | 639,486,000 |
In-service utility plant, net |  | 1,278,584,000 | 1,113,545,000 |
Construction work in progress | [2],[3],[4] | 111,707,000 | 138,663,000 |
MGE [Member] | Electric [Member] | Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross | [2],[4] | 1,480,701,000 | 1,310,438,000 |
MGE [Member] | Gas [Member] | Regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 472,134,000 | 442,593,000 |
MGE [Member] | Non Regulated Energy [Member] | Non-regulated [Member] |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |
In-service utility plant, gross |  | 323,266,000 | 322,855,000 |
Less: Accumulated depreciation and amortization |  | 71,623,000 | 66,605,000 |
In-service utility plant, net |  | 251,643,000 | 256,250,000 |
Construction work in progress |  | $ 777,000 | $ 1,008,000 |
[1] | MGE's utility plant is subject to the lien of its Indenture of Mortgage and Deed of Trust, under which its first mortgage bonds are issued. The Mortgage Indenture provides that dividends or any other distribution or purchase of MGE shares may not be made if the aggregate amount thereof since December 31, 1945, would exceed the earned surplus (retained earnings) accumulated subsequent to December 31, 1945. As of December 31, 2019, approximately $465.2 million was available for the payment of dividends under this covenant.
[2] | As of December 31, 2018, MGE has classified $3.1 million of Columbia assets as held-for-sale on the consolidated balance sheets related to the partial sale of plant assets to WPL. See Footnote 6.a. for further discussion.
[3] | 2019 includes construction expenditures for Badger Hollow I and Two Creeks. See Footnote 6 for further information.
[4] | In December 2017, the PSCW authorized construction of a 66 MW wind farm, consisting of 33 turbines, located near Saratoga, Iowa. The project was placed in service in February 2019. Total capitalized expenditures of the project were $107.9 million,including $4.1 million of AFUDC. MGE received specific approval to recover 100% AFUDC on the project.

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