Columbia Environmental Project Construction	9 Months Ended
Sep. 30, 2014
Regulated Operations [Abstract]
Columbia Environmental Project Construction	Columbia Environmental Project Construction - MGE Energy and MGE. MGE and two other utilities jointly own Columbia, a coal-fired generating facility. WPL is the plant operator and permit holder, and owns 46.2% of Columbia. WPSC owns a 31.8% interest, and MGE owns a 22% interest, in Columbia. In early 2011, the PSCW issued a Certificate and Order authorizing the construction of scrubbers and baghouses and associated equipment on Columbia Units 1 and 2 to reduce SO₂ and mercury emissions. The modifications to Unit 2 were placed into service in April 2014, and the modifications to Unit 1 were placed into service in July 2014. The scrubbers and baghouses are expected to support compliance obligations for current and anticipated air quality regulations, including CAIR, CSAPR, MATS, and the Wisconsin Mercury Rule. As of September 30, 2014, $138.6 million of the capitalized project was transferred from Construction work in progress to Property, plant, and equipment on MGE's balance sheet related to Units 1 and 2 being placed into service. This total amount consisted of $128.8 million of capital expenditures and $9.8 million of AFUDC. MGE's share of various contractual commitments entered for the project as of September 30, 2014 is $5.5 million. For the three months ended September 30, 2014 and 2013, MGE has recognized after tax $0.1 million and $0.8 million, respectively, in AFUDC equity related to this project. For the nine months ended September 30, 2014 and 2013, MGE has recognized after tax $3.0 million and $1.9 million, respectively, in AFUDC equity related to this project. MGE expects that the costs pertaining to this project will be fully recoverable through rates. For 2014, the PSCW authorized MGE 100% AFUDC on this project during construction. For 2013, the PSCW authorized MGE a 50% current return (included in customer rates) and the remaining 50% as AFUDC.

Columbia Environmental Project Construction - MGE Energy and MGE.

MGE and two other utilities jointly own Columbia, a coal-fired generating facility. WPL is the plant operator and permit holder, and owns 46.2% of Columbia. WPSC owns a 31.8% interest, and MGE owns a 22% interest, in Columbia. In early 2011, the PSCW issued a Certificate and Order authorizing the construction of scrubbers and baghouses and associated equipment on Columbia Units 1 and 2 to reduce SO₂ and mercury emissions. The modifications to Unit 2 were placed into service in April 2014, and the modifications to Unit 1 were placed into service in July 2014. The scrubbers and baghouses are expected to support compliance obligations for current and anticipated air quality regulations, including CAIR, CSAPR, MATS, and the Wisconsin Mercury Rule. As of September 30, 2014, $138.6 million of the capitalized project was transferred from Construction work in progress to Property, plant, and equipment on MGE's balance sheet related to Units 1 and 2 being placed into service. This total amount consisted of $128.8 million of capital expenditures and $9.8 million of AFUDC. MGE's share of various contractual commitments entered for the project as of September 30, 2014 is $5.5 million. For the three months ended September 30, 2014 and 2013, MGE has recognized after tax $0.1 million and $0.8 million, respectively, in AFUDC equity related to this project. For the nine months ended September 30, 2014 and 2013, MGE has recognized after tax $3.0 million and $1.9 million, respectively, in AFUDC equity related to this project.

MGE expects that the costs pertaining to this project will be fully recoverable through rates. For 2014, the PSCW authorized MGE 100% AFUDC on this project during construction. For 2013, the PSCW authorized MGE a 50% current return (included in customer rates) and the remaining 50% as AFUDC.