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Pension and Other Postretirement Plans | 9 Months Ended
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Sep. 30, 2021
Compensation and Retirement Disclosure [Abstract] |
Pension and Other Postretirement Plans | Pensi on and Other Postretirement Plans - MGE Energy and MGE. MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits and defined contribution 401(k) benefit plans for its employees and retirees. The components of net periodic benefit cost, other than the service cost component, are recorded in "Other income, net" on the consolidated statements of income. The service cost component is recorded in "Other operations and maintenance" on the consolidated statements of income. MGE has regulatory treatment and recognizes regulatory assets or liabilities for timing differences between when net periodic benefit costs are recovered and when costs are recognized. The following table presents the components of net periodic benefit costs recognized.
|  | Three Months Ended |  |  | Nine Months Ended |
|  | September 30, |  |  | September 30, |
(In thousands) |  | 2021 |  |  | 2020 |  |  | 2021 |  |  | 2020 |
Pension Benefits |  |  |  |  |  |  |  |  |  |  |  |
Components of net periodic benefit cost: |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 1,432 |  |  | $ | 1,324 |  |  | $ | 4,296 |  |  | $ | 3,972 |
Interest cost |  |  | 2,280 |  |  |  | 3,052 |  |  |  | 6,840 |  |  |  | 9,157 |
Expected return on assets |  |  | (7,372 | ) |  |  | (6,807 | ) |  |  | (22,115 | ) |  |  | (20,422 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |
Prior service credit |  |  | (31 | ) |  |  | (31 | ) |  |  | (93 | ) |  |  | (93 | )
Actuarial loss |  |  | 1,662 |  |  |  | 1,339 |  |  |  | 4,985 |  |  |  | 4,018 |
Net periodic benefit (credit) cost |  | $ | (2,029 | ) |  | $ | (1,123 | ) |  | $ | (6,087 | ) |  | $ | (3,368 | )
Postretirement Benefits |  |  |  |  |  |  |  |  |  |  |  |
Components of net periodic benefit cost: |  |  |  |  |  |  |  |  |  |  |  |
Service cost |  | $ | 362 |  |  | $ | 316 |  |  | $ | 1,086 |  |  | $ | 948 |
Interest cost |  |  | 387 |  |  |  | 570 |  |  |  | 1,161 |  |  |  | 1,709 |
Expected return on assets |  |  | (819 | ) |  |  | (789 | ) |  |  | (2,457 | ) |  |  | (2,366 | )
Amortization of: |  |  |  |  |  |  |  |  |  |  |  |
Transition obligation |  |  | 1 |  |  |  | 1 |  |  |  | 2 |  |  |  | 2 |
Prior service credit |  |  | (379 | ) |  |  | (667 | ) |  |  | (1,138 | ) |  |  | (2,001 | )
Actuarial loss |  |  | 123 |  |  |  | 55 |  |  |  | 370 |  |  |  | 165 |
Net periodic benefit (credit) cost |  | $ | (325 | ) |  | $ | (514 | ) |  | $ | (976 | ) |  | $ | (1,543 | )
As approved by the PSCW, MGE is allowed to defer differences between actual employee benefit plan costs and costs reflected in current rates. The deferred costs may be recovered or refunded in MGE's next rate filing. During the three and nine months ended September 30, 2021, MGE recovered $0.3 million and $3.9 million of pension and other postretirement costs, respectively, compared to $0.2 million and $0.7 million for the comparable periods in 2020. The recovery of these costs reduced the amount previously deferred and has not been reflected in the table above. During the three and nine months ended September 30, 2021, MGE deferred $2.8 million and $5.4 million, respectively, of savings from 2021 employee benefit plan costs and recorded as a regulatory liability. The deferred savings has not been reflected in the table above.

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