U.S. and Europe Retrospective Responsibility Plans - Schedule of Changes in the U.S. Litigation Escrow Account (Detail) - USD ($) $ in Millions	3 Months Ended
Dec. 31, 2024	Dec. 31, 2023
Escrow Account [Roll Forward]
Balance as of beginning of period	$ 3,089	$ 1,764
Balance as of end of period	3,112	1,616
Interest Income \| Opt-out Merchants
Escrow Account [Roll Forward]
Payments to opt-out merchants, net of interest earned on escrow funds	$ 23	$ (148)

Amount of cash and cash equivalents restricted as to withdrawal or usage. Cash includes, but is not limited to, currency on hand, demand deposits with banks or financial institutions, and other accounts with general characteristics of demand deposits. Cash equivalents include, but are not limited to, short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 230
-SubTopic 10
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-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
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Balance Type:	debit
Period Type:	instant