Loans and finance receivables - Schedule of reconciliation of allowance for credit losses on loans and finance receivables (Detail) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024
Allowance for Credit Loss [Abstract]
Balance at the beginning of the year	$ 1,134	$ 950
Provision for credit losses	253	116
Charge-offs, net of recoveries	(80)	(51)
Balance at June 30	$ 1,307	$ 1,015

Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Name:	us-gaap_FinancingReceivableAllowanceForCreditLosses
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant