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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The amount of goodwill arising from a business combination that is expected to be deductible for tax purposes.

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Amount of assets acquired at the acquisition date.

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Amount recognized as of the acquisition date for the identifiable assets acquired in excess of (less than) the aggregate liabilities assumed.

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Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Business Combinations and Asset Acquisitions (Details) - USD ($) $ in Millions	Sep. 30, 2023	Apr. 07, 2023	Dec. 31, 2022
Business Combination [Line Items]
Goodwill	$ 16,396		$ 14,852
Montana Rail Link
Business Combination [Line Items]
Property and equipment		$ 500
Materials and supplies		37
Goodwill		1,576
Fair value of assets		$ 2,113