Auditor's remuneration - Narrative (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
|
| Analysis of income and expense [abstract] | |||
| Remuneration for audit services to retirement benefit plans for employees of subsidiaries | $ 1 | $ 1 | $ 1 |