GOVERNMENT GRANTS	9 Months Ended
GOVERNMENT GRANTS	Sep. 30, 2024
Government Assistance [Abstract]
GOVERNMENT GRANTS	GOVERNMENT GRANTS Asset-Based Grants: In November 2020, the Company was awarded a Defense Production Act Title III technology investment agreement (“TIA”) from the Department of Defense (“DOD”) to establish domestic processing for separated light rare earth elements in the amount of $9.6 million. During the nine months ended September 30, 2024, the Company received $0.1 million in reimbursements from the DOD, which was the final reimbursement expected under the TIA. There were no reimbursements received for the nine months ended September 30, 2023. In February 2022, the Company was awarded a $35.0 million contract by the DOD’s Office of Industrial Base Analysis and Sustainment program to design and build a facility to process heavy rare earth elements (“HREE”) at Mountain Pass (the “HREE Facility”) (the “HREE Production Project Agreement”). During the nine months ended September 30, 2024 and 2023, the Company had received zero and $1.1 million, respectively, from the DOD under the HREE Production Project Agreement. Income-Based Grants: In August 2022, the U.S. government enacted the Inflation Reduction Act of 2022, which, among other things, promotes clean energy adoption by providing several tax incentives for the domestic production and sale of eligible components for tax years beginning after December 31, 2022. Specifically, the 45X Credit provides a credit equal to 10% of eligible “production costs incurred” with respect to the production and sale of critical minerals, including NdPr oxide. In October 2024, the Internal Revenue Service released final regulations on the 45X Credit, which among other things, added direct and indirect materials costs, including costs related to the extraction or acquisition of raw materials, to the definition of “production costs incurred,” which were previously excluded from the definition under the proposed regulations released in December 2023. The impact of the new guidance, including a cumulative adjustment to reflect the inclusion of direct and indirect costs on previous sales, will be accounted for in the fourth quarter of 2024. The Company accounts for the 45X Credit as an income-based grant as it is not within the scope of ASC 740 due to it being refundable. As of September 30, 2024 and December 31, 2023, the government grant receivable and deferred government grant within the Company’s unaudited Condensed Consolidated Balance Sheets pertained to the 45X Credit. During the third quarter of 2024, the Company received $19.4 million related to the 45X Credit claimed on its 2023 federal tax return. The current portion of deferred government grant, which is included in “Other current liabilities,” was $2.0 million and $1.7 million as of September 30, 2024 and December 31, 2023, respectively. For the three and nine months ended September 30, 2024, the benefits recognized in the Company’s unaudited Condensed Consolidated Statements of Operations pertaining to the 45X Credit, which are included as reductions to “Cost of sales (excluding depreciation, depletion and amortization) (including related party),” were $1.4 million and $3.8 million, respectively, and to “Depreciation, depletion and amortization,” were $0.5 million and $1.4 million, respectively. There were no benefits recognized from income-based government grants for the three and nine months ended September 30, 2023.