XML 125 R87.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Asset Retirement Obligations (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligations [Roll Forward]    
Asset retirement obligation, beginning balance $ 29,980 $ 26,738
Liabilities incurred [1] 1,586 1,943
Accretion expense 1,574 1,415
Liabilities settled (323) (175)
Revisions in estimated cash flows [2] (4,462) 59
Asset retirement obligation, ending balance 28,355 29,980
Forward Wind [Member]    
Asset Retirement Obligations [Roll Forward]    
Liabilities incurred   $ 1,600
Saratoga Wind Farm [Member]    
Asset Retirement Obligations [Roll Forward]    
Liabilities incurred $ 1,500  
[1] 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.
[2] In 2019, MGE revised the AROs associated with certain wind farms based on updated estimated decommissioning costs.