Variable Interest Entities - Schedule of Carrying Value of Consolidated Variable Interest Entities' Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025	Dec. 31, 2024
Current assets
Cash and cash equivalents	$ 8,119	$ 22,841
Total current assets	69,887	23,110
Non-current assets
Property and equipment, net	1,194	390
Mineral interests, which includes $0 and $2,275 related to SEM, respectively	23,615	23,327	$ 0
Other non-current assets	466	42
Total non-current assets	25,275	25,727
Total assets	95,162	48,837
Current liabilities
Accounts payable	1,986	1,486
Accrued expenses	1,402	1,211
Lease liability, current	226	23
Other current liabilities	200	13
Total current liabilities	3,814	3,856
Non-current liabilities
Other non-current liabilities	766	370
Total non-current liabilities	8,004	16,518
Total liabilities	11,818	20,374
Variable Interest Entity
Current assets
Cash and cash equivalents	148	10,922
Prepaid expenses and other current assets	443	118
Total current assets	591	11,040
Non-current assets
Property and equipment, net	873	362
Mineral interests, which includes $0 and $2,275 related to SEM, respectively	0	2,275
Other non-current assets	138	42
Total non-current assets	24,626	23,731
Total assets	25,217	34,771
Current liabilities
Accounts payable	429	362
Accrued expenses	551	22
Lease liability, current	91	23
Other current liabilities	55	11
Total current liabilities	1,126	418
Non-current liabilities
Other non-current liabilities	40	20
Total non-current liabilities	40	20
Total liabilities	1,166	438
Variable Interest Entity \| SEM
Non-current assets
Mineral interests, which includes $0 and $2,275 related to SEM, respectively	$ 23,615	$ 23,327

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).