Supplemental cash flow information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for income taxes	$ 7,765	$ 4,236	$ 5,412
Non-cash investing and financing activities:
Liabilities assumed in connection with business acquisitions	10,938	24,186	102
Operating lease liabilities arising from obtaining right-of-use assets	1,645	1,118	687
Insurance and Other [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	1,272	1,150	1,227
Railroad, Utilities and Energy [Member]
Supplemental Cash Flow Information [Line Items]
Cash paid during the period for interest	$ 3,725	$ 3,195	$ 3,162