Short-term investments (Narrative) (Details) - USD ($) $ in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Short-Term Investments [Line Items] | ||
| Short-term investments | $ 0.0 | $ 40.0 |
| Guaranteed investment certificate maturing March 2025 [Member] | ||
| Short-Term Investments [Line Items] | ||
| Short-term investments | 20.0 | |
| Guaranteed investment certificate maturing June 2025 [Member] | ||
| Short-Term Investments [Line Items] | ||
| Short-term investments | $ 20.0 |