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ASSET RETIREMENT OBLIGATIONS | 12 Months Ended
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Dec. 31, 2024
ASSET RETIREMENT OBLIGATIONS |
ASSET RETIREMENT OBLIGATIONS | 15.ASSET RETIREMENT OBLIGATIONS ​ The following table presents the activity affecting the asset retirement and mine closing liability: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Year Ended December 31, |
​ |  | 2024 |  | 2023 |
​ | ​ | (in thousands) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Beginning balance | ​ | $ | 150,443 | ​ | $ | 149,813 | ​
Accretion expense | ​ |  | 4,528 | ​ |  | 4,433 | ​
Payments | ​ |  | (1,770) | ​ |  | (2,317) | ​
Allocation of liability associated with mine development and change in assumptions | ​ |  | 5,576 | ​ |  | (1,486) | ​
Ending balance | ​ | $ | 158,777 | ​ | $ | 150,443 | ​
​ For the year ended December 31, 2024, the allocation of liability associated with mine development and change in assumptions increased by $5.6 million. The increase was largely attributable to higher cost assumptions. ​ 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. ​ The impact of discounting our estimated cash flows resulted in reducing the accrual for asset retirement obligations by $120.1 million and $116.2 million at December 31, 2024 and 2023, respectively. Estimated payments of asset retirement obligations as of December 31, 2024 are as follows: ​
​ | ​ | ​ | ​ | ​
Year Ended | ​ | ​ | ​ | ​
December 31, |  | (in thousands) |
​ | ​ | ​ | ​ | ​
2025 | ​ | $ | 3,621 | ​
2026 | ​ |  | 4,763 | ​
2027 | ​ |  | 7,043 | ​
2028 | ​ |  | 9,312 | ​
2029 | ​ |  | 9,584 | ​
Thereafter | ​ |  | 244,592 | ​
Aggregate undiscounted asset retirement obligations | ​ |  | 278,915 | ​
Less: effect of discounting | ​ |  | (120,138) | ​
Total asset retirement obligations | ​ |  | 158,777 | ​
Less: current portion | ​ |  | (3,621) | ​
Non-current asset retirement obligations | ​ | $ | 155,156 | ​
​ As of December 31, 2024 and 2023, we had approximately $170.1 million and $173.5 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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