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Pension and Other Postretirement Plans | 3 Months Ended
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Mar. 31, 2015
Compensation and Retirement Disclosure [Abstract] |
Pension and Other Postretirement Plans | Pension and Other Postretirement Plans - MGE Energy and MGE. MGE maintains qualified and nonqualified pension plans, health care, and life insurance benefits. Additionally, MGE has def ined contribution 401(k) benefit plans. The following table presents the components of MGE Energy's and MGE's net periodic benefit costs recognized for the three months ended March 31, 2015 and 2014. A portion of the net periodic benefit cost is capitalized within the consolidated balance she ets.
|  |  | Three Months Ended |
|  |  | March 31, |
| (In thousands) |  | 2015 |  | 2014 |
| Pension Benefits |  |  |  |  |
| Components of net periodic cost (benefit): |  |  |  |  |
| Service cost | $ | 1,798 | $ | 1,484 |
| Interest cost |  | 3,440 |  | 3,251 |
| Expected return on assets |  | (5,677) |  | (5,279) |
| Amortization of: |  |  |  |  |
| Prior service cost |  | 6 |  | 49 |
| Actuarial loss |  | 1,334 |  | 173 |
| Net periodic cost (benefit) | $ | 901 | $ | (322) |
| Postretirement Benefits |  |  |  |  |
| Components of net periodic cost (benefit): |  |  |  |  |
| Service cost | $ | 383 | $ | 330 |
| Interest cost |  | 778 |  | 772 |
| Expected return on assets |  | (703) |  | (654) |
| Amortization of: |  |  |  |  |
| Transition obligation |  | 1 |  | 1 |
| Prior service benefit |  | (667) |  | (668) |
| Actuarial loss |  | 262 |  | 39 |
| Net periodic cost (benefit) | $ | 54 | $ | (180) |

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- Definition The entire disclosure for pension and other postretirement benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -URI http://asc.fasb.org/topic&trid=2235017 + Details
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