Supplemental cash flow information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for income taxes	$ 2,896	$ 1,352
Non-cash investing activity - liabilities assumed in connection with business acquisitions	793	4,991
Borrowings assumed in connection with certain property, plant and equipment additions	306	376
Wesco Financial Corporation [Member]
Supplemental Cash Flow Information [Line Items]
Common stock issued in connection with acquisition of noncontrolling interests		245
Insurance and Other [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	290	155
Railroad, Utilities and Energy [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	1,393	1,390
Finance and Financial Products [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	$ 471	$ 475

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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The amount of cash paid for interest during the period net of cash paid for interest that is capitalized.

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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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