Supplemental cash flow information (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for income taxes	$ 382	$ 392
Non-cash investing and financing activities:
Liabilities assumed in connection with business acquisitions	1,285	9
Insurance and Other [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	449	435
Railroad, Utilities and Energy [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	$ 978	$ 905

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.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-4

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 3
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-3

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482913/230-10-50-5

Name:	us-gaap_NoncashOrPartNoncashAcquisitionValueOfLiabilitiesAssumed1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration