Financial instruments and risk management - Foreign Exchange Exposures (Details) - USD ($) $ in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Forward foreign exchange contracts | ||
| Risk management | ||
| Notional amount | $ 1,400 | $ 2,400 |
| Currency risk | United States of America, Dollars | ||
| Risk management | ||
| Increase (decrease) in net borrowings that would result from decreased currency value, per sensitivity analysis | $ 45 | $ 40 |
| Maximum | Forward foreign exchange contracts | ||
| Risk management | ||
| Period of time of hedge contracts (in years) | 3 years | 1 year |