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Asset Retirement Obligations (Tables) | 3 Months Ended
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Mar. 31, 2017
Asset Retirement Obligation Disclosure [Abstract] |
Activity Related to Asset Retirement Obligations | Activity related to the Company’s asset retirement obligations is as follows:
(In thousands) |  | Three Months Ended March 31, 2017
Balance at beginning of period |  | $ | 133,733 |
Liabilities incurred |  | 702 |
Liabilities settled |  | (696 | )
Accretion expense |  | 1,787 |
Balance at end of period |  | $ | 135,526 |

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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://www.xbrl.org/2003/role/presentationRef -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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