Exploration and Evaluation Assets - Schedule of Exploration and Evaluation Assets Relating to Thacker Pass Project (Details) - Exploration and Evaluation Assets - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Acquisition costs | ||
| Total exploration and evaluation assets, beginning balance | $ 343,794 | $ 343,092 |
| Additions | 229 | 702 |
| Write offs | (3,009) | |
| Total exploration and evaluation assets, ending balance | 341,014 | 343,794 |
| Millennial Projects | ||
| Acquisition costs | ||
| Total exploration and evaluation assets, beginning balance | 342,409 | 341,707 |
| Additions | 229 | 702 |
| Write offs | (3,009) | |
| Total exploration and evaluation assets, ending balance | 339,629 | 342,409 |
| Other Claims | ||
| Acquisition costs | ||
| Total exploration and evaluation assets, beginning balance | 1,385 | 1,385 |
| Additions | 0 | 0 |
| Total exploration and evaluation assets, ending balance | $ 1,385 | $ 1,385 |