Variable Interest Entities and Securitizations - Carrying Amount of Assets and Liabilities of Variable Interest Entities (Detail) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	$ 34,537	$ 37,157
Carrying Amount of Liabilities, Consolidated	16,425	12,449
Carrying Amount of Assets, Unconsolidated	4,019	3,796
Carrying Amount of Liabilities, Unconsolidated	535	519
Maximum exposure to loss	4,681	4,451
Affordable housing entities
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	0
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	3,744	3,500
Carrying Amount of Liabilities, Unconsolidated	506	488
Maximum exposure to loss	3,744	3,500
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	370	374
Carrying Amount of Liabilities, Consolidated	100	99
Carrying Amount of Assets, Unconsolidated	0	1
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum exposure to loss	0	1
Other
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	4
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	61	74
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum exposure to loss	61	74
Total Other VIEs
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	370	378
Carrying Amount of Liabilities, Consolidated	100	99
Carrying Amount of Assets, Unconsolidated	3,805	3,575
Carrying Amount of Liabilities, Unconsolidated	506	488
Maximum exposure to loss	3,805	3,575
Credit card loan securitizations
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	34,167	36,779
Carrying Amount of Liabilities, Consolidated	16,325	12,350
Carrying Amount of Assets, Unconsolidated	0	0
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum exposure to loss	0	0
Home loan
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	0
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	214	221
Carrying Amount of Liabilities, Unconsolidated	29	31
Maximum exposure to loss	876	876
Total securitization-related VIEs
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	34,167	36,779
Carrying Amount of Liabilities, Consolidated	16,325	12,350
Carrying Amount of Assets, Unconsolidated	214	221
Carrying Amount of Liabilities, Unconsolidated	29	31
Maximum exposure to loss	$ 876	$ 876

The carrying amount of the consolidated Variable Interest Entity's assets included in the reporting entity's statement of financial position.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=52262685&loc=d3e5710-111685

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Balance Type:	debit
Period Type:	instant

- Definition

The carrying amount of the consolidated Variable Interest Entity's liabilities included in the reporting entity's statement of financial position.

+ References

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=52262685&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=52262685&loc=d3e5747-111685

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- Definition

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.

+ References

No definition available.

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- Definition

Carrying amount of the assets in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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- Definition

Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary.

+ References

+ Details

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