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FAIR VALUE MEASUREMENTS | 3 Months Ended
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Mar. 31, 2025
FAIR VALUE MEASUREMENTS |
FAIR VALUE MEASUREMENTS | 4.FAIR VALUE MEASUREMENTS ​ The following table summarizes certain fair value measurements within the hierarchy not included elsewhere in these notes: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | Fair Value | ​
​ |  | Carrying Value |  | Level 1 |  | Level 2 |  | Level 3 |
​ | ​ | (in thousands) | ​
March 31, 2025 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Recorded on a recurring basis: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Digital assets | ​ | $ | 42,323 | ​ | $ | 42,323 | ​ | $ | — | ​ | $ | — | ​
Contingent consideration | ​ | $ | 11,324 | ​ | $ | — | ​ | $ | — | ​ | $ | 11,324 | ​
Additional disclosures: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Long-term debt | ​ | $ | 483,754 | ​ | $ | — | ​ | $ | 508,931 | ​ | $ | — | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
December 31, 2024 | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Recorded on a recurring basis: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Digital assets | ​ | $ | 45,037 | ​ | $ | 45,037 | ​ | $ | — | ​ | $ | — | ​
Contingent consideration | ​ | $ | 13,100 | ​ | $ | — | ​ | $ | — | ​ | $ | 13,100 | ​
Additional disclosures: | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Long-term debt | ​ | $ | 490,387 | ​ | $ | — | ​ | $ | 523,461 | ​ | $ | — | ​
​ The carrying amounts for cash equivalents, accounts receivable, accounts payable, accrued and other liabilities approximate fair value due to the short maturity of those instruments. ​ The fair value of our digital assets is based on an exchange quoted price. See Note 6 – Digital Assets for more information on our digital assets. ​ The fair value measurement of our contingent consideration liability is determined using an option approach methodology simulation based on significant inputs not observable in active markets representing a Level 3 fair value measurement under the fair value hierarchy. Our contingent consideration liability is associated with our acquisition of our Hamilton mine in 2015 wherein we agreed to pay the seller additional consideration for the acquisition if the average quarterly sales price exceeds a defined threshold price in any future quarters subject to a maximum of $110.0 million reduced for any payments made under an overriding royalty agreement with the sellers relating to mineral interests controlled by our Hamilton mine. We have paid $11.4 million under this contingent consideration agreement and nothing under the overriding royalty agreement as of March 31, 2025. ​ The estimated fair value of our long-term debt, including current maturities, is based on interest rates that we believe are currently available to us in active markets for issuance of debt with similar terms and remaining maturities. See Note 8 – Long-Term Debt for additional information on our long-term debt. ​ Quantitative Information about Level 3 Fair Value Measurements ​ Our option approach methodology simulation generates an expected payment for each quarter in Hamilton’s mine life by using proprietary internal estimates of our uncommitted coal sales prices and generating a simulated uncommitted coal sales price by applying unobservable inputs through a million simulations. This simulated coal sales price is then used in a calculation of the expected future payments using our proprietary committed coal sales prices and production for each quarter. We then calculate the present value of the estimated future payments. The following table presents quantitative information about certain significant unobservable inputs used in the fair value measurement for our contingent consideration liability. The use of significant unobservable inputs results in uncertainty as of the reporting date, as changes in these unobservable inputs could significantly raise or lower the estimated fair value. ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ |  | Valuation Technique(s) |  | Unobservable Input |  | Range/Amount (Average) (a) | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
March 31, 2025 | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Contingent Consideration | ​ | Option approach methodology simulation | ​ | Cost of Debt | ​ | 6.51% - 8.56% | ​
​ | ​ | ​ | ​ | Coal price volatility | ​ | 6.2% | ​
​ | ​ | ​ | ​ | Market price of risk adjustment (annual) | ​ | 6.2% | ​
December 31, 2024 | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
Contingent Consideration | ​ | Option approach methodology simulation | ​ | Cost of Debt | ​ | 6.51% - 8.56% | ​
​ | ​ | ​ | ​ | Coal price volatility | ​ | 6.2% | ​
​ | ​ | ​ | ​ | Market price of risk adjustment (annual) | ​ | 6.2% | ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
(a) Averages represent the arithmetic average of the inputs and is not weighted by a relative fair value or notional amount | ​
​ The following table represents changes in our contingent consideration liability: ​
​ | ​ | ​ | ​ | ​ | ​ | ​ | ​
​ | ​ | Three Months Ended | ​
​ | ​ | March 31, | ​
​ |  | 2025 | ​ | 2024 |
​ | ​ | (in thousands) | ​
Beginning balance | ​ | $ | 13,100 | ​ | $ | 9,900 | ​
Payments | ​ | ​ | (1,776) | ​ | ​ | (1,431) | ​
Ending balance | ​ | $ | 11,324 | ​ | $ | 8,469 | ​
​

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- Definition The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 107 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-107 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 100 -Publisher FASB -URI https://asc.fasb.org/1943274/2147482078/820-10-55-100 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(3) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2E -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E Reference 6: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 7: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (f) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 8: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (e) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 9: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 6A -Subparagraph (d) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A Reference 10: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (h) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 11: http://www.xbrl.org/2003/role/disclosureRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (g) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 12: http://www.xbrl.org/2003/role/disclosureRef -Topic 940 -SubTopic 820 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478119/940-820-50-1 + Details
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