Share-Based Compensation	9 Months Ended
Sep. 30, 2020
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Share-Based Compensation	Share-Based Compensation - MGE Energy and MGE. a. 2013 Director Incentive Plan and 2006 Performance Unit Plan Under MGE Energy's 2013 Director Incentive Plan (the 2013 Plan) and its 2006 Performance Unit Plan (the 2006 Plan), non-employee directors and eligible employees, respectively, 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 performance period set in the award. In accordance with the plans' provisions, these awards are subject to prescribed vesting schedules and must be settled in cash. Accordingly, no shares of common stock will be issued in connection with the plans. In 2020, 5,048 units were granted under the 2013 Plan and are subject to a three-year graded vesting schedule. No units were granted under the 2006 Plan in 2020 in view of the adoption of the 2020 Performance Unit Plan described below. On the grant date, the cost of the director or employee services received in exchange for a performance unit award is measured based on the current market value of MGE Energy common stock. The fair value of the awards is remeasured quarterly, including as of September 30, 2020, as required by applicable accounting standards. Changes in quarterly fair value as well as the original grant are recognized as compensation cost. Since this amount is remeasured throughout the vesting period, the compensation cost is subject to variability. For nonretirement eligible employees under the 2006 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 as retirement eligibility accelerates vesting. During the three months ended September 30, 2020 and 2019, MGE recorded $0.1 million and $0.9 million, respectively, in compensation expense as a result of awards under the 2013 Plan and 2006 Plan. During the nine months ended September 30, 2020 and 2019, MGE recorded $0.3 million in compensation benefit and $2.8 million in compensation expense, respectively, as a result of awards under the 2013 Plan and 2006 Plan. In January 2020, cash payments of $2.0 million were distributed relating to awards that were granted in a prior year under the plans. No forfeitures of units occurred during the three and nine months ended September 30, 2020 and 2019. As of September 30, 2020, $3.4 million of outstanding awards are vested. Of this amount, no cash settlements have occurred as cash payments are only made at the end of the period covered by the awards. b. 2020 Performance Unit Plan The 2020 Performance Unit Plan (the 2020 Plan) was adopted in February 2020 for eligible employees. Plan participants may receive awards of performance units, restricted units, or both. Performance units 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, based upon achievement of specified performance goals during a performance period set by the Compensation Committee of MGE Energy's Board of Directors. Restricted units 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 a defined time period. Awards are subject to vesting provisions providing for 100% vesting at the end of the performance period, in the case of performance units, and at the end of the defined time period in the case of restricted units. The performance units and restricted units will be paid out in cash and are accounted for as a liability award. No shares of common stock will be issued in connection with the 2020 Plan. In April 2020, 9,822 performance units and 9,822 restricted units were granted under the 2020 Plan. The 2020 performance units contain market and performance conditions. The market condition is based on total shareowner return relative to an investor-owned utility peer group. The performance condition is based on achievement of targets specified in the award agreement (such as an earnings growth target). The fair value of each performance unit is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market and performance conditions contained in the award agreement during the three-year performance period. The actual payments upon vesting depends upon actual performance and may range from zero to 200% of the granted number of performance units. The 2020 restricted units will vest based on a three-year cliff vesting schedule. During the three and nine months ended September 30, 2020, MGE recorded less than $0.1 million and $0.6 million, respectively, in compensation expense as a result of awards under the 2020 Plan.

Share-Based Compensation

9 Months Ended

Sep. 30, 2020

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Share-Based Compensation - MGE Energy and MGE.

2013 Director Incentive Plan and 2006 Performance Unit Plan

Under MGE Energy's 2013 Director Incentive Plan (the 2013 Plan) and its 2006 Performance Unit Plan (the 2006 Plan), non-employee directors and eligible employees, respectively, 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 performance period set in the award. In accordance with the plans' provisions, these awards are subject to prescribed vesting schedules and must be settled in cash. Accordingly, no shares of common stock will be issued in connection with the plans.

In 2020, 5,048 units were granted under the 2013 Plan and are subject to a three-year graded vesting schedule. No units were granted under the 2006 Plan in 2020 in view of the adoption of the 2020 Performance Unit Plan described below. On the grant date, the cost of the director or employee services received in exchange for a performance unit award is measured based on the current market value of MGE Energy common stock. The fair value of the awards is remeasured quarterly, including as of September 30, 2020, as required by applicable accounting standards. Changes in quarterly fair value as well as the original grant are recognized as compensation cost. Since this amount is remeasured throughout the vesting period, the compensation cost is subject to variability.

For nonretirement eligible employees under the 2006 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 as retirement eligibility accelerates vesting.

During the three months ended September 30, 2020 and 2019, MGE recorded $0.1 million and $0.9 million, respectively, in compensation expense as a result of awards under the 2013 Plan and 2006 Plan. During the nine months ended September 30, 2020 and 2019, MGE recorded $0.3 million in compensation benefit and $2.8 million in compensation expense, respectively, as a result of awards under the 2013 Plan and 2006 Plan. In January 2020, cash payments of $2.0 million were distributed relating to awards that were granted in a prior year under the plans. No forfeitures of units occurred during the three and nine months ended September 30, 2020 and 2019. As of September 30, 2020, $3.4 million of outstanding awards are vested. Of this amount, no cash settlements have occurred as cash

payments are only made at the end of the period covered by the awards.

2020 Performance Unit Plan

The 2020 Performance Unit Plan (the 2020 Plan) was adopted in February 2020 for eligible employees. Plan participants may receive awards of performance units, restricted units, or both. Performance units 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, based upon achievement of specified performance goals during a performance period set by the Compensation Committee of MGE Energy's Board of Directors. Restricted units 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 a defined time period. Awards are subject to vesting provisions providing for 100% vesting at the end of the performance period, in the case of performance units, and at the end of the defined time period in the case of restricted units. The performance units and restricted units will be paid out in cash and are accounted for as a liability award. No shares of common stock will be issued in connection with the 2020 Plan.

In April 2020, 9,822 performance units and 9,822 restricted units were granted under the 2020 Plan. The 2020 performance units contain market and performance conditions. The market condition is based on total shareowner return relative to an investor-owned utility peer group. The performance condition is based on achievement of targets specified in the award agreement (such as an earnings growth target). The fair value of each performance unit is based on the fair value of the underlying common stock on the grant date and the probability of satisfying the market and performance conditions contained in the award agreement during the three-year performance period. The actual payments upon vesting depends upon actual performance and may range from zero to 200% of the granted number of performance units. The 2020 restricted units will vest based on a three-year cliff vesting schedule.

During the three and nine months ended September 30, 2020, MGE recorded less than $0.1 million and $0.6 million, respectively, in compensation expense as a result of awards under the 2020 Plan.