Property, plant and equipment - Depreciation expense (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 5,471	$ 4,982
Insurance and Other [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	1,966	1,568
Railroad, Utilities and Energy [Member]
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 3,505	$ 3,414

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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+ Details