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ASSET RETIREMENT OBLIGATION | 12 Months Ended
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Dec. 31, 2020
ASSET RETIREMENT OBLIGATION |
ASSET RETIREMENT OBLIGATION | 7.ASSET RETIREMENT OBLIGATION The information below details the asset retirement obligation for the years ended December 31, 2020 and 2019 as follows (in thousands):
​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | December 31,
​ |  | 2020 |  | 2019
Beginning balance at January 1, | ​ | $ | 5,759 | ​ | $ | 6,092
Asset retirement obligation |  | ​ | 771 |  | ​ | 850
Settlement of asset retirement obligation |  | ​ | (1,375) |  | ​ | —
Retirement cost revaluation |  | ​ | (1,235) |  | ​ | (1,486)
Accretion expense |  | ​ | 217 |  | ​ | 303
Ending balance at December 31, | ​ | $ | 4,137 | ​ | $ | 5,759
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- Definition The entire disclosure for an asset retirement obligation and the associated long-lived asset. An asset retirement obligation is a legal obligation associated with the disposal or retirement from service of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -URI http://asc.fasb.org/subtopic&trid=2175671 + Details
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