Lease liabilities - Contractual maturities (Details) - USD ($) $ in Millions |
9 Months Ended | |
|---|---|---|
Sep. 30, 2026 |
Dec. 31, 2025 |
|
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Carrying value | $ 380.6 | $ 372.4 |
| Total contractual cash flows | $ 705.1 | 698.9 |
| Weighted average | ||
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Average remaining lease term | 11 years | |
| Within one year | ||
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Total contractual cash flows | $ 74.4 | 69.8 |
| 2-3 years | ||
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Total contractual cash flows | 143.0 | 140.0 |
| 4-5 years | ||
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Total contractual cash flows | 112.1 | 111.3 |
| Over 5 years | ||
| Disclosure of quantitative information about right-of-use assets [line items] | ||
| Total contractual cash flows | $ 375.6 | $ 377.8 |