Deferred revenue (Schedule of changes in deferred revenue) (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Disclosure of Deferred Revenue [Abstract] | ||
| Stream accounting - Deferred revenue, beginning balance | $ 372.2 | $ 418.5 |
| Amortization of deferred revenue | ||
| Liability drawdown | (65.1) | (74.3) |
| Variable consideration adjustments - prior periods | (9.9) | 3.8 |
| Accretion on streaming arrangements | ||
| Current year additions | 20.5 | 24.0 |
| Variable consideration adjustments - prior periods | (0.6) | 0.2 |
| Stream accounting - Deferred revenue, ending balance | $ 317.1 | $ 372.2 |