Supplementary cash flow information (Narrative) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Supplementary Cash Flow Information [Line Items] | ||
| Increase (decrease) to property, plant and equipment assets due to remeasurements of decommissioning and restoration liabilities | $ (0.2) | $ (4.7) |
| Deduction for accrued grants related to equipment eligible for credits | 2.8 | 0.0 |
| Plant and equipment - ROU assets [Member] | Cost [Member] | ||
| Supplementary Cash Flow Information [Line Items] | ||
| Additions | 17.7 | 25.5 |
| Equipment financing [Member] | ||
| Supplementary Cash Flow Information [Line Items] | ||
| Additions | 33.1 | 71.0 |
| Agreements with communities [Member] | ||
| Supplementary Cash Flow Information [Line Items] | ||
| Additions | $ 39.5 | $ 18.6 |