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ASSET RETIREMENT OBLIGATIONS AND RESTRICTED CASH (Tables) | 6 Months Ended
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Jun. 30, 2018
Asset Retirement Obligation Disclosure [Abstract] |
Schedule of Change in Asset Retirement Obligation | The following table summarizes the Company’s asset retirement obligations:
| June 30, 2018 |  | December 31, 2017
Asset retirement obligation, beginning of period | $ | 18,280 |  |  | $ | 17,033 |
Revision of estimate | — |  |  | 249 |
Accretion of liabilities | 917 |  |  | 1,733 |
Settlements | (151 | ) |  | (735 | )
Asset retirement obligation, end of period | $ | 19,046 |  |  | $ | 18,280 |
Asset retirement obligation: |  |  |
Current | $ | 32 |  |  | $ | 32 |
Non-current | 19,014 |  |  | 18,248 |
Asset retirement obligation, end of period | $ | 19,046 |  |  | $ | 18,280 |
Schedule of Restricted Cash and Cash Equivalents | The following table summarizes the Company’s restricted cash:
| June 30, 2018 |  | December 31, 2017
Restricted cash, beginning of period | $ | 22,127 |  |  | $ | 23,175 |
Additional collateral posted | 102 |  |  | 13,609 |
Refunds of collateral | (635 | ) |  | (14,657 | )
Restricted cash, end of period | $ | 21,594 |  |  | $ | 22,127 |
Cash, cash equivalents and restricted cash are included in the following accounts at June 30, 2018 and December 31, 2017:
| June 30, 2018 |  | December 31, 2017
Cash and cash equivalents | $ | 43,239 |  |  | $ | 18,574 |
Restricted cash included in other long-term assets | 21,594 |  |  | 22,127 |
Total cash, cash equivalents and restricted cash | $ | 64,833 |  |  | $ | 40,701 |

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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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