Derivative financial instruments - Fair value (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Derivatives | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | $ 23.5 | $ 19.2 |
| Embedded options within listed bonds | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | 33.6 | 29.4 |
| Foreign exchange swaps | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | $ (10.1) | $ (10.2) |