Property, plant and equipment - Depreciation expense (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Property, Plant and Equipment [Line Items] | |||
| Depreciation expense | $ 10,146 | $ 9,631 | $ 9,392 |
| Insurance and Other [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Depreciation expense | 3,245 | 3,117 | 2,898 |
| Railroad, Utilities and Energy [Member] | |||
| Property, Plant and Equipment [Line Items] | |||
| Depreciation expense | $ 6,901 | $ 6,514 | $ 6,494 |