Other receivables - Narrative (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Aggregate provisions for credit losses on receivables	$ 513	$ 409	$ 441
Charge-offs, net of recoveries	474	432	$ 420
Railroad, Utilities and Energy [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	6,034	$ 4,182
Railroad, Utilities and Energy [Member] | PTC [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Trade receivables	$ 2,100