Retirement benefits - Summary of Retirement Benefit Expense (Details) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Defined benefit plans: | |||
| Interest income on plan assets | $ (3,153) | $ (2,999) | $ (3,417) |
| Other | (31) | (467) | 252 |
| Total | 560 | 295 | 850 |
| Defined contribution plans | 515 | 514 | 474 |
| Total retirement benefit expense | 1,075 | 809 | 1,324 |
| Pensions | |||
| Defined benefit plans: | |||
| Current service cost, net of plan participants' contributions | 680 | 802 | 731 |
| Interest expense on defined pension benefit obligations | 2,769 | 2,757 | 3,072 |
| OPEB | |||
| Defined benefit plans: | |||
| Current service cost, net of plan participants' contributions | 31 | 38 | 36 |
| Interest expense on defined pension benefit obligations | 172 | 154 | 166 |
| Asset ceilings | |||
| Defined benefit plans: | |||
| Interest expense on defined pension benefit obligations | $ 92 | $ 10 | $ 10 |