| Line Item | Jun 30, 2026 | Mar 31, 2026 | Dec 31, 2025 | Sep 30, 2025 | Jun 30, 2025 | Mar 31, 2025 | Dec 31, 2024 | Sep 30, 2024 | Jun 30, 2024 | Mar 31, 2024 | Dec 31, 2023 | Sep 30, 2023 | Jun 30, 2023 | Mar 31, 2023 | Dec 31, 2022 | Sep 30, 2022 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Operating expenses: | ||||||||||||||||
| General and administrative costs | ||||||||||||||||
| Exploration and development costs | ||||||||||||||||
| Mine site costs | ||||||||||||||||
| Depreciation and amortization | ||||||||||||||||
| Asset retirement obligation adjustments and accretion | ||||||||||||||||
| Other (income) expense, net | — | — | ||||||||||||||
| Loss from operations | ||||||||||||||||
| Non-operating income (expense): | ||||||||||||||||
| Interest income | ||||||||||||||||
| Other income (loss), net | ||||||||||||||||
| Interest expense | ||||||||||||||||
| Net loss | ||||||||||||||||
| Basic (in dollars per share) | ||||||||||||||||
| Diluted (in dollars per share) |