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Commitments, Contingencies, Guarantees, and Others - Litigation (Detail) $ in Millions	1 Months Ended	6 Months Ended
	Oct. 31, 2018 USD ($)	Jun. 30, 2020 USD ($) claim
Loss Contingencies [Line Items]
Loss contingency, estimate of possible loss		$ 1,000
Anti-money laundering
Loss Contingencies [Line Items]
Litigation settlement paid	$ 100
Cybersecurity Incident [Member]
Loss Contingencies [Line Items]
Number of consumer class action cases filed for Cybersecurity Incident | claim		73
Penalty to the US Treasury Accrued		$ 80
Pending litigation | Interchange litigation
Loss Contingencies [Line Items]
Litigation settlement, attributable to reporting entity and third party		$ 5,500
United States | Cybersecurity Incident [Member]
Loss Contingencies [Line Items]
Number of consumer class action cases filed for Cybersecurity Incident | claim		61
Canada | Cybersecurity Incident [Member]
Loss Contingencies [Line Items]
Number of consumer class action cases filed for Cybersecurity Incident | claim		12

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Litigation Settlement, Amount Attributable to Reporting Entity and Third Party

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Number of consumer class action cases filed for Cybersecurity Incident

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Amount awarded to other party in judgment or settlement of litigation.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14435-108349

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=121557415&loc=d3e14557-108349

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=121555522&loc=d3e12021-110248

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