Decommissioning provision (Narrative) (Details) - Provision for decommissioning, restoration and rehabilitation costs [Member] - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Decommissioning Provision [Line Items] | ||
| Estimated undiscounted amount of decommissioning provision | $ 16.0 | $ 19.8 |
| Bottom of range [Member] | ||
| Decommissioning Provision [Line Items] | ||
| Term used to estimate decommissioning provision | 5 years | 5 years |
| Risk-free rate | 3.60% | 3.70% |
| Top of range [Member] | ||
| Decommissioning Provision [Line Items] | ||
| Term used to estimate decommissioning provision | 21 years | 14 years |
| Risk-free rate | 9.10% | 10.40% |