Supplemental cash flow information (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for income taxes	$ 4,395	$ 3,977
Liabilities assumed in connection with business acquisitions	147	93
Right-of-use assets obtained in exchange for new operating lease liabilities	526
Insurance and Other [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	879	934
Railroad, Utilities and Energy [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	$ 2,149	$ 2,129

Supplemental Cash Flow Information [Line Items]

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- Definition

The amount of cash paid during the current period to foreign, federal, state, and local authorities as taxes on income, net of any cash received during the current period as refunds for the overpayment of taxes.

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Amount of cash paid for interest, including, but not limited to, capitalized interest and payment to settle zero-coupon bond attributable to accreted interest of debt discount and debt instrument with insignificant coupon interest rate in relation to effective interest rate of borrowing attributable to accreted interest of debt discount; classified as operating and investing activities.

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- Definition

The total amount of [all] liabilities that an Entity assumes in acquiring a business or in consideration for an asset received in a noncash (or part noncash) acquisition. Noncash is defined as transactions during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

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- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

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