Financial risk management (Details 2) - USD ($) $ in Millions |
Jun. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Notes and other explanatory information [abstract] | ||
| Open derivative transactions | $ 24 | $ (24) |
| Closed derivative transactions awaiting financial settlement | (5) | (5) |
| Recognized in Statements of Financial Position | 19 | (29) |
| Other assets (note 17) | 103 | 102 |
| Other liabilities (note 17) | $ (84) | $ (131) |