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ASSET RETIREMENT OBLIGATIONS | 12 Months Ended
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Dec. 31, 2022
ASSET RETIREMENT OBLIGATIONS |
ASSET RETIREMENT OBLIGATIONS | 20.ASSET RETIREMENT OBLIGATIONS ​ The following table presents the activity affecting the asset retirement and mine closing liability: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31, |
​ |  | 2022 |  | 2021 |
​ | ​ | (in thousands) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Beginning balance | ​ | $ | 131,099 | ​ | $ | 127,898 | ​
Accretion expense | ​ |  | 3,731 | ​ |  | 3,688 | ​
Payments | ​ |  | (2,445) | ​ |  | (1,383) | ​
Allocation of liability associated with mine development and change in assumptions | ​ |  | 17,428 | ​ |  | 896 | ​
Ending balance | ​ | $ | 149,813 | ​ | $ | 131,099 | ​
​ For the year ended December 31, 2022, the allocation of liability associated with mine development and change in assumptions increased by $17.4 million. The increase was largely attributable to higher cost assumptions as well as the expansion of refuse disposal facilities at certain mines. ​ For the year ended December 31, 2021, the allocation of liability associated with mine development and change in assumptions was immaterial. ​ The impact of discounting our estimated cash flows resulted in reducing the accrual for asset retirement obligations by $110.4 million and $98.3 million at December 31, 2022 and 2021, respectively. Estimated payments of asset retirement obligations as of December 31, 2022 are as follows: ​
​ | ​ | ​ | ​ | ​
Year Ended | ​ | ​ | ​ | ​
December 31, |  | (in thousands) |
​ | ​ | ​ | ​ | ​
2023 | ​ | $ | 7,559 | ​
2024 | ​ |  | 4,936 | ​
2025 | ​ |  | 1,935 | ​
2026 | ​ |  | 1,569 | ​
2027 | ​ |  | 3,182 | ​
Thereafter | ​ |  | 241,065 | ​
Aggregate undiscounted asset retirement obligations | ​ |  | 260,246 | ​
Effect of discounting | ​ |  | (110,433) | ​
Total asset retirement obligations | ​ |  | 149,813 | ​
Less: current portion | ​ |  | (7,559) | ​
Non-current asset retirement obligations | ​ | $ | 142,254 | ​
​ As of December 31, 2022 and 2021, we had approximately $174.3 million and $173.9 million, respectively, in surety bonds outstanding to secure the performance of our reclamation obligations. ​ See Note 2 – Summary of Significant Accounting Policies for more information on our accounting policy for asset retirement obligations.

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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://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=6392692&loc=d3e7569-110849 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -URI https://asc.fasb.org/subtopic&trid=2175671 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 410 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=6392692&loc=d3e7535-110849 + Details
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