Mineral Properties, Plant and Equipment, Net - Schedule of Mineral Properties, Plant and Equipment, Net (Parenthetical) (Details) - USD ($) $ in Thousands |
6 Months Ended | 9 Months Ended | 12 Months Ended |
|---|---|---|---|
Jun. 30, 2026 |
Dec. 31, 2025 |
Dec. 31, 2025 |
|
| Property, Plant and Equipment [Line Items] | |||
| Discount amortization | $ 2,170 | $ 3,403 | |
| Deferred interest cost | 5,522 | 12,978 | |
| Thacker Pass [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Prepaid construction costs | 88,800 | 75,000 | $ 75,000 |
| Interest on other loans | 3,400 | 3,200 | |
| Deferred interest on DOE loan | 18,300 | 2,300 | |
| Discount amortization | 15,900 | 9,100 | |
| Deferred interest cost | 18,500 | 13,000 | |
| Deposits on long-lead equipment | $ 243,800 | $ 268,700 | $ 268,700 |