Commitments and Contingencies	9 Months Ended
Commitments and Contingencies	Sep. 30, 2024
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Surety Bonds and Restricted Cash As the owner of the Five Forks Mine, the Company is required to post a surety bond with a regulatory commission related to performance requirements associated with the Five Forks Mine. As of September 30, 2024, the amount of this surety bond was $7.5 million. The Company leases land adjacent to the Corbin Facility and is required to post surety bonds with a regulatory commission for reclamation. As of September 30, 2024, the amount of these surety bonds was $3.0 million. The Company holds permits for an abandoned mine in West Virginia ("Mine 4") and is required to post a surety bond with a regulatory commission for reclamation. As of September 30, 2024, the amount of this surety bond was $0.7 million. As of September 30, 2024 and December 31, 2023, the Company posted cash collateral of $8.5 million and $8.5 million, respectively, as required by the Company's surety bond providers, which is reported as long-term restricted cash in the Condensed Consolidated Balance Sheets. As of September 30, 2024, the Company holds a deposit of $0.4 million with a third party for collateral as required under a bonding arrangement for Mine 4. This deposit is included in "Other long-term assets, net" in the Condensed Consolidated Balance Sheet as of September 30, 2024. The Company has a customer supply agreement that requires the Company to post a performance bond in an amount equal to the annual contract value of $3.7 million. As of September 30, 2024, the remaining commitment under this customer contract, which expires on December 31, 2024, was approximately $1.3 million. Red River Plant Construction Contract In January 2024, the Company executed a contract with a third-party contractor for the construction of a GAC facility at the Red River Plant, and immediately commenced construction operations. The Company terminated the contract in September 2024, and anticipates completing construction and commissioning with internal resources fulfilling the role of the third-party contractor. The Company expects to complete its first deliveries in the first quarter of 2025 and estimates that total construction costs will be in the range of $75.0 - $80.0 million. Tinuum Group The Company has certain limited obligations contingent upon future events in connection with the activities of Tinuum Group. The Company, NexGen Refined Coal, LLC ("NexGen") and two entities affiliated with NexGen have provided another Tinuum Group owner with limited guarantees (the "Tinuum Group Party Guarantees") related to certain losses it may suffer as a result of inaccuracies or breach of representations and covenants. The Company also is a party to a contribution agreement with NexGen under which any party called upon to pay on a Tinuum Group Party Guaranty is entitled to receive contribution from the other party equal to 50% of the amount paid. No liability or expense provision has been recorded by the Company related to this contingent obligation as the Company believes that it is not probable that a loss will occur with respect to Tinuum Group Party Guarantees. As of September 30, 2024 and December 31, 2023, the Company has a contractual obligation (the "Tinuum Group Obligation") of $1.7 million for its share of certain contingent liabilities of Tinuum Group as required under the Distribution and Repayment Agreement (the "Repayment Agreement") that was executed in December 2022 by the Company and certain owners of Tinuum Group. The Tinuum Group Obligation is included in the "Other current liabilities" line item in the Consolidated Balance Sheet. Legal Proceedings The Company is from time to time subject to various pending or threatened legal actions and proceedings, including those that arise in the ordinary course of its business. Such matters are subject to many uncertainties and outcomes, the financial impacts of which are not predictable with assurance and that may not be known for extended periods of time. The Company records a liability in its consolidated financial statements for costs related to claims, settlements and judgments where management has assessed that a loss is probable and an amount can be reasonably estimated. As of September 30, 2024, there were no material pending legal proceedings to which the Company is a party.