Share-Based Compensation	3 Months Ended
Share-Based Compensation	Mar. 31, 2017
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation - MGE Energy and MGE. Under MGE Energy's Director Incentive Plan and Performance Unit Plan, non-employee directors and eligible employees may receive performance units that entitle the holder to receive a cash payment equal to the value of a designated number of shares of MGE Energy's common stock, plus dividend equivalent payments thereon, at the end of the set performance period. In January 2017, 4,032 units were granted under the Director Incentive Plan and are subject to a three-year graded vesting schedule. In March 2017, 14,704 units were granted under the Performance Unit Plan and are subject to a five-year graded vesting schedule. On the grant date, MGE Energy and MGE measure the cost of the director or employee services received in exchange for a performance unit award based on the current market value of MGE Energy common stock. The fair value of the awards is re-measured quarterly, including at March 31, 2017, as required by applicable accounting standards. Changes in fair value as well as the original grant are recognized as compensation cost. Since this amount is re-measured throughout the vesting period, the compensation cost is subject to variability. For nonretirement eligible employees under the Performance Unit Plan, stock based compensation costs are accrued and recognized using the graded vesting method. Compensation cost for retirement eligible employees or employees that will become retirement eligible during the vesting schedule are recognized on an abridged horizon. During the three months ended March 31, 2017, MGE recorded $0.5 million in compensation expense as a result of awards under the plans compared to $1.3 million for the comparable period in 2016. In January 2017, cash payments of $2.0 million were distributed relating to awards that were granted under the plans. No forfeitures of units occurred during the three months ended March 31, 2017 and 2016. At March 31, 2017, $5.4 million of outstanding awards are vested, and of this amount, no cash settlements have occurred.

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.