Equity and Financing Arrangements	9 Months Ended
Sep. 30, 2015
Equity and Financing Arrangements Disclosure [Abstract]
Equity and Financing Arrangements	Equity and Financing Arrangements. a. Common Stock - MGE Energy. 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 both the nine months ended September 30, 2015 and 2014, MGE Energy did not issue any new shares of common stock under the Stock Plan. b. Dilutive Shares Calculation - MGE Energy. MGE Energy does not hold any dilutive securities. c. Credit Facilities - MGE Energy and MGE. On June 1, 2015, MGE Energy and MGE entered into new revolving credit agreements, and terminated their existing revolving credit agreements. MGE Energy entered into a Credit Agreement with an aggregate commitment of $50 million (MGE Energy Credit Agreement) with various financial institutions, as lenders, and JPMorgan Chase Bank, N.A., as administrative agent. Also, MGE entered into two revolving credit agreements: a Credit Agreement with an aggregate commitment of $60 million (MGE JPM Credit Agreement) with various financial institutions, as lenders, and JPMorgan Chase Bank, N.A., as administrative agent, and a Credit Agreement with an aggregate commitment of $40 million (MGE USB Credit Agreement) with various financial institutions, as lenders, and U.S. Bank National Association, as administrative agent. The MGE Energy Credit Agreement, the MGE JPM Credit Agreement, and the MGE USB Credit Agreement are collectively referred to as the Credit Agreements. As of September 30, 2015, neither MGE Energy nor MGE had any borrowings outstanding under the Credit Agreements, and MGE had no commercial paper outstanding. The Credit Agreements have a term expiring on June 1, 2020. Borrowings under the Credit Agreements may bear interest at a rate based upon either a "floating rate" or a "Eurodollar Rate" adjusted for statutory reserve requirements, plus an adder based upon the credit ratings assigned to MGE's senior unsecured long-term debt securities. The "floating rate" is calculated on a daily basis as the highest of a prime rate, a Federal Funds effective rate plus 0.5% per annum, or a Eurodollar Rate for a one-month interest period plus 1%. The "floating rate" adder ranges from zero to 0.125%. The "Eurodollar Rate" is calculated as provided in the Credit Agreements. The "Eurodollar Rate" adder ranges from 0.625% to 1.125%.

Equity and Financing Arrangements

9 Months Ended

Sep. 30, 2015

Equity and Financing Arrangements Disclosure [Abstract]

Equity and Financing Arrangements.

a. Common Stock - MGE Energy.

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 both the nine months ended September 30, 2015 and 2014, MGE Energy did not issue any new shares of common stock under the Stock Plan.

b. Dilutive Shares Calculation - MGE Energy.

MGE Energy does not hold any dilutive securities.

c. Credit Facilities - MGE Energy and MGE.

On June 1, 2015, MGE Energy and MGE entered into new revolving credit agreements, and terminated their existing revolving credit agreements.

MGE Energy entered into a Credit Agreement with an aggregate commitment of $50 million (MGE Energy Credit Agreement) with various financial institutions, as lenders, and JPMorgan Chase Bank, N.A., as administrative agent. Also, MGE entered into two revolving credit agreements: a Credit Agreement with an aggregate commitment of $60 million (MGE JPM Credit Agreement) with various financial institutions, as lenders, and JPMorgan Chase Bank, N.A., as administrative agent, and a Credit Agreement with an aggregate commitment of $40 million (MGE USB Credit Agreement) with various financial institutions, as lenders, and U.S. Bank National Association, as administrative agent. The MGE Energy Credit Agreement, the MGE JPM Credit Agreement, and the MGE USB Credit Agreement are collectively referred to as the Credit Agreements. As of September 30, 2015, neither MGE Energy nor MGE had any borrowings outstanding under the Credit Agreements, and MGE had no commercial paper outstanding.

The Credit Agreements have a term expiring on June 1, 2020. Borrowings under the Credit Agreements may bear interest at a rate based upon either a "floating rate" or a "Eurodollar Rate" adjusted for statutory reserve requirements, plus an adder based upon the credit ratings assigned to MGE's senior unsecured long-term debt securities. The "floating rate" is calculated on a daily basis as the highest of a prime rate, a Federal Funds effective rate plus 0.5% per annum, or a Eurodollar Rate for a one-month interest period plus 1%. The "floating rate" adder ranges from zero to 0.125%. The "Eurodollar Rate" is calculated as provided in the Credit Agreements. The "Eurodollar Rate" adder ranges from 0.625% to 1.125%.