Columbia Environmental Project Construction	3 Months Ended
Mar. 31, 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 bag houses and associated equipment on Columbia Units 1 and 2 to reduce SO₂ and mercury emissions. Unit 2 was placed into service in April 2014 and Unit 1 is expected to be placed into service in the third quarter of 2014. The scrubbers and bag houses are expected to support compliance obligations for current and anticipated air quality regulations, including CAIR, CSAPR, the Mercury and Air Toxics Standards (MATS), and the Wisconsin Mercury Rule. The operator's current estimate shows that MGE's share of the capital expenditures required for this project is approximately $135 million. As of March 31, 2014, MGE had accumulated $124.3 million (excluding carrying costs) related to its share of the project, which is reflected in the Construction Work in Progress balance on MGE Energy's and MGE's consolidated balance sheets. MGE expects to incur capital expenditures of approximately $10.7 million for the remainder of 2014. These amounts may change as a result of modifications to the project estimate or timing differences. MGE's share of various contractual commitments entered for the project as of March 31, 2014 is $10.7 million. For the three months ended March 31, 2014 and 2013, MGE has recognized after tax $1.9 million and $0.5 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 bag houses and associated equipment on Columbia Units 1 and 2 to reduce SO₂ and mercury emissions. Unit 2 was placed into service in April 2014 and Unit 1 is expected to be placed into service in the third quarter of 2014. The scrubbers and bag houses are expected to support compliance obligations for current and anticipated air quality regulations, including CAIR, CSAPR, the Mercury and Air Toxics Standards (MATS), and the Wisconsin Mercury Rule. The operator's current estimate shows that MGE's share of the capital expenditures required for this project is approximately $135 million. As of March 31, 2014, MGE had accumulated $124.3 million (excluding carrying costs) related to its share of the project, which is reflected in the Construction Work in Progress balance on MGE Energy's and MGE's consolidated balance sheets. MGE expects to incur capital expenditures of approximately $10.7 million for the remainder of 2014. These amounts may change as a result of modifications to the project estimate or timing differences. MGE's share of various contractual commitments entered for the project as of March 31, 2014 is $10.7 million. For the three months ended March 31, 2014 and 2013, MGE has recognized after tax $1.9 million and $0.5 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.