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ASSET RETIREMENT OBLIGATIONS | 12 Months Ended
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Dec. 31, 2023
ASSET RETIREMENT OBLIGATIONS |
ASSET RETIREMENT OBLIGATIONS | 18.ASSET RETIREMENT OBLIGATIONS ​ The following table presents the activity affecting the asset retirement and mine closing liability: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31, |
​ |  | 2023 |  | 2022 |
​ | ​ | (in thousands) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Beginning balance | ​ | $ | 149,813 | ​ | $ | 131,099 | ​
Accretion expense | ​ |  | 4,433 | ​ |  | 3,731 | ​
Payments | ​ |  | (2,317) | ​ |  | (2,445) | ​
Allocation of liability associated with mine development and change in assumptions | ​ |  | (1,486) | ​ |  | 17,428 | ​
Ending balance | ​ | $ | 150,443 | ​ | $ | 149,813 | ​
​ For the year ended December 31, 2023, the allocation of liability associated with mine development and change in assumptions decreased by $1.5 million. The decrease was largely attributable to lower cost assumptions. ​ 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. ​ The impact of discounting our estimated cash flows resulted in reducing the accrual for asset retirement obligations by $116.2 million and $110.4 million at December 31, 2023 and 2022, respectively. Estimated payments of asset retirement obligations as of December 31, 2023 are as follows: ​
​ | ​ | ​ | ​ | ​
Year Ended | ​ | ​ | ​ | ​
December 31, |  | (in thousands) |
​ | ​ | ​ | ​ | ​
2024 | ​ | $ | 3,518 | ​
2025 | ​ |  | 5,557 | ​
2026 | ​ |  | 4,063 | ​
2027 | ​ |  | 7,038 | ​
2028 | ​ |  | 4,291 | ​
Thereafter | ​ |  | 242,134 | ​
Aggregate undiscounted asset retirement obligations | ​ |  | 266,601 | ​
Less: effect of discounting | ​ |  | (116,158) | ​
Total asset retirement obligations | ​ |  | 150,443 | ​
Less: current portion | ​ |  | (3,518) | ​
Non-current asset retirement obligations | ​ | $ | 146,925 | ​
​ As of December 31, 2023 and 2022, we had approximately $173.5 million and $174.3 million, respectively, in surety bonds outstanding to secure the performance of our reclamation 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 -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 410 -SubTopic 20 -Name Accounting Standards Codification -Publisher FASB -URI https://asc.fasb.org//410-20/tableOfContent Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name Accounting Standards Codification -Section 50 -Paragraph 2 -SubTopic 20 -Topic 410 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481850/410-20-50-2 + Details
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