DEBT OBLIGATIONS - Interest Expense, Net (Details) - USD ($) $ in Thousands |
3 Months Ended | 9 Months Ended | |||
|---|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
Dec. 31, 2025 |
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| Debt Instrument [Line Items] | |||||
| Amortization of debt discount and debt issuance costs | $ 5,430 | $ 3,572 | |||
| Other interest cost(1) | $ 2,531 | $ 786 | 7,142 | 1,302 | |
| Interest capitalized to property, plant and equipment, net | (3,281) | (1,527) | (8,703) | (4,114) | |
| Interest expense, net | 9,409 | 8,566 | 28,958 | 21,595 | |
| Interest Payable | 4,500 | 4,500 | $ 10,900 | ||
| Convertible Debt | |||||
| Debt Instrument [Line Items] | |||||
| Coupon interest | 6,471 | 6,513 | 19,455 | 19,539 | |
| Amortization of debt issuance costs | 997 | 1,050 | 3,051 | 3,124 | |
| Interest Expense, Debt | 7,468 | 7,563 | 22,506 | 22,663 | |
| Notes Payable, Other Payables | Samarium Project Loan | |||||
| Debt Instrument [Line Items] | |||||
| Coupon interest | 2,017 | 1,345 | 6,052 | 1,345 | |
| Amortization of debt discount and debt issuance costs | 674 | 399 | 1,961 | 399 | |
| Interest Expense, Debt | $ 2,691 | $ 1,744 | $ 8,013 | $ 1,744 | |
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- Definition Amount of amortization expense attributable to debt issuance costs. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount of amortization expense attributable to debt discount (premium) and debt issuance costs. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of interest capitalized during the period. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of the cost of borrowed funds accounted for as interest expense for debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Represents the portion of interest incurred in the period on debt arrangements that was charged against earnings, excluding amortization of debt discount (premium) and financing costs. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Amount of interest expense classified as nonoperating. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of interest expense classified as other. No definition available.
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- Definition Amount of interest payable on debt, including, but not limited to, trade payables. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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