Derivative financial instruments - Fair value (Details) - USD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Derivatives | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | $ 29.0 | $ 48.1 |
| Embedded options within listed bonds | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | 42.0 | $ 48.1 |
| Nondeliverable forwards | ||
| Derivative financial instruments | ||
| Derivative financial instruments at fair value | $ (13.0) |