Pension and other postretirement benefits - Schedule of Healthcare Cost Trend (Details) - Other Postretirement Benefits Plan - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| U.S. | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Healthcare cost trend rate assumed for next year | 8.20% | 7.90% | 7.20% |
| Rate to which the cost trend rate gradually declines | 4.50% | 4.50% | 4.50% |
| Year the rate reaches the ultimate rate | 2035 | 2033 | 2031 |
| Accumulated postretirement benefit obligation | $ 44 | $ 49 | |
| Non-U.S. | |||
| Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] | |||
| Healthcare cost trend rate assumed for next year | 5.10% | 5.00% | 4.60% |
| Rate to which the cost trend rate gradually declines | 4.00% | 4.00% | 4.00% |
| Year the rate reaches the ultimate rate | 2040 | 2040 | 2040 |
| Accumulated postretirement benefit obligation | $ 71 | $ 70 | |