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Asset Retirement Obligations (Tables) | 12 Months Ended
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Dec. 31, 2019
Asset Retirement Obligation Disclosure [Abstract] |
Change in Asset Retirement Obligations | The following table summarizes the change in AROs. Amounts include conditional AROs
| (In thousands) |  | 2019 |  | 2018 |
| Balance as of January 1, | $ | 29,980 | $ | 26,738 |
| Liabilities incurred(a) |  | 1,586 |  | 1,943 |
| Accretion expense |  | 1,574 |  | 1,415 |
| Liabilities settled |  | (323) |  | (175) |
| Revisions in estimated cash flows(b) |  | (4,462) |  | 59 |
| Balance as of December 31, | $ | 28,355 | $ | 29,980 |
(a)In 2019, MGE recorded an obligation of $1.5 million for the fair value of its legal liability for AROs associated with Saratoga. See Footnote 4 for additional information on Saratoga. In 2018, MGE recorded an obligation of $1.6 million for the fair value of its legal liability for AROs associated with Forward Wind. See Footnote 6 for additional information on Forward Wind. (b)In 2019, MGE revised the AROs associated with certain wind farms based on updated estimated decommissioning costs.

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- Definition Tabular disclosure of the changes in carrying amount of a liability for asset retirement obligations, for changes such as new obligations, changes in estimates of existing obligations, spending on existing obligations, property dispositions, and foreign currency translation. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13201-110859 + Details
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