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Long-term Supply Agreement, Agreed Prepayment Amount

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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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.

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Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

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Amount of transaction price allocated to performance obligation that has not been recognized as revenue.

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REVENUE RECOGNITION - Narrative (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 14, 2025	Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025	Dec. 31, 2025
Disaggregation of Revenue [Line Items]
Revenue (including related party)		$ 147,655	$ 53,553	$ 346,794	$ 171,756
Current deferred revenue		32,304		32,304		$ 74,301
Non-current deferred revenue		88,121		88,121		$ 83,889
Revenue, Remaining Performance Obligation, Amount		179,500		179,500
Operating Segments
Disaggregation of Revenue [Line Items]
Revenue (including related party)		152,162		357,570
Operating Segments \| Materials Segment
Disaggregation of Revenue [Line Items]
Revenue (including related party)		133,539	31,641	301,345	124,792
General Motors Company
Disaggregation of Revenue [Line Items]
Current deferred revenue		27,600		27,600
Apple
Disaggregation of Revenue [Line Items]
Current deferred revenue		4,200		4,200
Future prepayments under long-term supply agreement	$ 200,000
Contract With Customer, Liability, Cumulative Additions		80,000		80,000
Non-current deferred revenue		75,800		75,800
SEG+ \| Operating Segments \| Materials Segment
Disaggregation of Revenue [Line Items]
Revenue (including related party)		31,600		31,600
Revenue Under Bill-and-Hold Arrangement
Disaggregation of Revenue [Line Items]
Revenue (including related party)		$ 82,800	$ 21,900	$ 177,400	$ 47,000