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Asset Retirement Obligations | 12 Months Ended
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Dec. 31, 2020
Asset Retirement Obligation Disclosure [Abstract] |
Asset Retirement Obligations | Asset Retirement Obligations Activity related to the Company's asset retirement obligations is as follows:
|  | Year Ended December 31,
(In thousands) |  | 2020 |  | 2019
Balance at beginning of period |  | $ | 72,098 |  |  | $ | 51,622 |
Liabilities incurred |  | 10,008 |  |  | 7,646 |
Liabilities settled |  | (322) |  |  | (1,467) |
Accretion expense |  | 4,205 |  |  | 3,430 |
Change in estimate |  | — |  |  | 10,867 |
Balance at end of period |  | 85,989 |  |  | 72,098 |
Less: current asset retirement obligation |  | (500) |  |  | (500) |
Noncurrent asset retirement obligation |  | $ | 85,489 |  |  | $ | 71,598 |

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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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