Precious metals delivery and purchase agreement (Details) - Metal Agreement [Member] - USD ($) $ in Thousands |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2025 |
Dec. 31, 2024 |
|
| Statement [Line Items] | ||
| Net metals contract liability, beginning of year | $ 40,868 | $ 36,837 |
| Advance increase (net of financing expense) | 0 | 12,512 |
| Delivery of metals purchased | 12,691 | 18,564 |
| Revaluation of metals contract liability | 16,441 | 10,083 |
| Net metals contract liability, end of year | 44,618 | 40,868 |
| Current portion | 20,024 | 13,707 |
| Non-current portion | 24,594 | 27,161 |
| Total | $ 44,618 | $ 40,868 |