Loans and finance receivables - Schedule of reconciliation of allowance for credit losses on loans and finance receivables (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
Allowance for Credit Loss [Abstract]
Balance at the beginning of the year	$ 1,347	$ 1,134
Provision for credit losses	52	183
Charge-offs, net of recoveries	(45)	(41)
Balance at March 31	$ 1,354	$ 1,276

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