Common Equity	12 Months Ended
Dec. 31, 2017
Equity [Abstract]
Common Equity	Common Equity. a. Common Stock - MGE Energy and MGE. MGE Energy sells shares of its common stock through its Stock Plan. Those shares may be newly issued shares or shares that MGE Energy has purchased in the open market for resale to participants in the Stock Plan. All sales under the Stock Plan are covered by a shelf registration statement that MGE Energy filed with the SEC. For the years ended December 31, 2017 and 2016, MGE Energy did not issue any new shares of common stock under the Stock Plan. MGE Energy's transfer agent purchases shares on the open market to provide shares to meet obligations to participants in the Stock Plan. The shares are purchased on the open market through their securities broker-dealer and then are reissued under the Stock Plan as needed to meet share delivery requirements. The volume and timing of share repurchases in the open market depends upon the level of dividend reinvestment and optional share purchases being made from time to time by plan participants. As a result, there is no specific maximum number of shares to be repurchased and no specified termination date for the repurchases. During the years ended December 31, 2017 and 2016, MGE Energy paid $43.7 million (or $1.26 per share) and $41.8 million (or $1.21 per share), respectively, in cash dividends on its common stock. Dividend payments by MGE to MGE Energy are subject to restrictions arising under a PSCW rate order and, to a lesser degree, MGE's first mortgage bonds. The PSCW order restricts any dividends, above the PSCW authorized amount that MGE may pay MGE Energy if its common equity ratio, calculated in the manner used in the rate proceeding, is less than 55%. See Footnote 9 for further discussion of the mortgage indenture covenants. During the years ended December 31, 2017 and 2016, MGE paid $45.0 million and $50.0 million, respectively, in cash dividends to MGE Energy. In 2016, MGE also transferred its ownership interest in MGE Transco to MGE Energy in the form of a dividend in kind of $15.8 million. See Footnote 4 for further information. b. Dilutive Shares Calculation - MGE Energy. MGE Energy does not hold any dilutive securities.

Common Equity.

a. Common Stock - MGE Energy and MGE.

MGE Energy sells shares of its common stock through its Stock Plan. Those shares may be newly issued shares or shares that MGE Energy has purchased in the open market for resale to participants in the Stock Plan. All sales under the Stock Plan are covered by a shelf registration statement that MGE Energy filed with the SEC. For the years ended December 31, 2017 and 2016, MGE Energy did not issue any new shares of common stock under the Stock Plan.

MGE Energy's transfer agent purchases shares on the open market to provide shares to meet obligations to participants in the Stock Plan. The shares are purchased on the open market through their securities broker-dealer and then are reissued under the Stock Plan as needed to meet share delivery requirements. The volume and timing of share repurchases in the open market depends upon the level of dividend reinvestment and optional share purchases being made from time to time by plan participants. As a result, there is no specific maximum number of shares to be repurchased and no specified termination date for the repurchases.

During the years ended December 31, 2017 and 2016, MGE Energy paid $43.7 million (or $1.26 per share) and $41.8 million (or $1.21 per share), respectively, in cash dividends on its common stock. Dividend payments by MGE to MGE Energy are subject to restrictions arising under a PSCW rate order and, to a lesser degree, MGE's first mortgage bonds. The PSCW order restricts any dividends, above the PSCW authorized amount that MGE may pay MGE Energy if its common equity ratio, calculated in the manner used in the rate proceeding, is less than 55%. See Footnote 9 for further discussion of the mortgage indenture covenants. During the years ended December 31, 2017 and 2016, MGE paid $45.0 million and $50.0 million, respectively, in cash dividends to MGE Energy. In 2016, MGE also transferred its ownership interest in MGE Transco to MGE Energy in the form of a dividend in kind of $15.8 million. See Footnote 4 for further information.

b. Dilutive Shares Calculation - MGE Energy.

MGE Energy does not hold any dilutive securities.