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Exploration and Evaluation Expenditures - Summary of Company's Exploration and Evaluation Expenditures (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Thacker Pass and Other Project Expenditures      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures $ 10,078 $ 21,214 $ 4,733
Thacker Pass and Other Project Expenditures | Geological, Consulting and Salaries      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 6,013 9,239 1,700
Thacker Pass and Other Project Expenditures | Permitting and Environmental      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 222   5
Thacker Pass and Other Project Expenditures | Field Supplies and Other      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 2,289 5,996 2,673
Thacker Pass and Other Project Expenditures | Depreciation      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 207 468 199
Thacker Pass and Other Project Expenditures | Drilling and Geological Expenses      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 1,347 5,511 156
Millennial Projects      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 8,437 18,051 4,733
Millennial Projects | Geological, Consulting and Salaries      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 4,372 6,086 1,700
Millennial Projects | Permitting and Environmental      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 222   5
Millennial Projects | Field Supplies and Other      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 2,289 5,986 2,673
Millennial Projects | Depreciation      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 207 468 199
Millennial Projects | Drilling and Geological Expenses      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 1,347 5,511 $ 156
Other Project      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures 1,641 3,163  
Other Project | Geological, Consulting and Salaries      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures $ 1,641 3,153  
Other Project | Field Supplies and Other      
Disclosure Of Exploration Expenditures [Line Items]      
Total exploration expenditures   $ 10