Variable Interest Entities and Securitizations - Carrying Amount of Assets and Liabilities of Variable Interest Entities (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	$ 32,995	$ 35,152
Carrying Amount of Liabilities, Consolidated	16,929	17,026
Carrying Amount of Assets, Unconsolidated	4,072	4,120
Carrying Amount of Liabilities, Unconsolidated	535	582
Maximum exposure to loss	5,150	4,782
Affordable housing entities
Variable Interest Entity [Line Items]
Variable Interest Entity, Nonconsolidated, Total Assets	11,100	11,400
Carrying Amount of Assets, Consolidated	174	0
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	3,803	3,852
Carrying Amount of Liabilities, Unconsolidated	508	555
Maximum exposure to loss	3,803	3,852
Entities that provide capital to low-income and rural communities
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	732	352
Carrying Amount of Liabilities, Consolidated	127	101
Carrying Amount of Assets, Unconsolidated	0	0
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum exposure to loss	0	0
Other
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	0	0
Carrying Amount of Liabilities, Consolidated	0	0
Carrying Amount of Assets, Unconsolidated	66	57
Carrying Amount of Liabilities, Unconsolidated	0	0
Maximum exposure to loss	66	57
Total Other VIEs
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	906	352
Carrying Amount of Liabilities, Consolidated	127	101
Carrying Amount of Assets, Unconsolidated	3,869	3,909
Carrying Amount of Liabilities, Unconsolidated	508	555
Maximum exposure to loss	3,869	3,909
GreenPoint Manufactured Housing
Variable Interest Entity [Line Items]
Carrying Amount of Liabilities, Unconsolidated	8	8
Maximum exposure to loss	420
Credit card loan securitizations
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	32,089	34,800
Carrying Amount of Liabilities, Consolidated	16,802	16,925
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	203	211
Carrying Amount of Liabilities, Unconsolidated	27	27
Maximum exposure to loss	1,281	873
Total securitization-related VIEs
Variable Interest Entity [Line Items]
Carrying Amount of Assets, Consolidated	32,089	34,800
Carrying Amount of Liabilities, Consolidated	16,802	16,925
Carrying Amount of Assets, Unconsolidated	203	211
Carrying Amount of Liabilities, Unconsolidated	27	27
Maximum exposure to loss	$ 1,281	$ 873

Variable Interest Entity, Nonconsolidated, Total Assets

No definition available.

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- Definition

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

+ References

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=64801991&loc=d3e5710-111685

+ Details

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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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Namespace Prefix:	us-gaap_
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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=64801991&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=64801991&loc=d3e5747-111685

+ Details

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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.

+ Details

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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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