Taxes	3 Months Ended
Mar. 31, 2017
Income Tax Disclosure [Abstract]
Taxes	Taxes - MGE Energy and MGE. Effective Tax Rate. MGE Energy's effective income tax rate for the three months ended March 31, 2017 and 2016, was 36.7% and 36.9%, respectively. MGE's effective income tax rate for the three months ended March 31, 2017 and 2016, was 36.2% and 36.8%, respectively. For both MGE Energy and MGE, the decrease in the effective tax rate is due in part to a higher estimated domestic manufacturing deduction and higher estimated AFUDC equity earnings in 2017. In addition, MGE's effective income tax rate decreased as a result of the transfer of its ownership interest in MGE Transco.

Taxes

3 Months Ended

Mar. 31, 2017

Taxes - MGE Energy and MGE.

Effective Tax Rate.

MGE Energy's effective income tax rate for the three months ended March 31, 2017 and 2016, was 36.7% and 36.9%, respectively. MGE's effective income tax rate for the three months ended March 31, 2017 and 2016, was 36.2% and 36.8%, respectively. For both MGE Energy and MGE, the decrease in the effective tax rate is due in part to a higher estimated domestic manufacturing deduction and higher estimated AFUDC equity earnings in 2017. In addition, MGE's effective income tax rate decreased as a result of the transfer of its ownership interest in MGE Transco.