Guarantees and Contingent Liabilities - Summary of Other Guarantees and Contingent Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2016	Dec. 31, 2015
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Carrying Amount	$ 70
Maximum Potential Future Payments	12,866
Third Party Borrowing Arrangements [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	72
Securities Lending Indemnifications [Member]
Guarantor Obligations [Line Items]
Collateral Held	6,388
Maximum Potential Future Payments	6,323
Asset Sales [Member]
Guarantor Obligations [Line Items]
Carrying Amount	110
Maximum Potential Future Payments	5,484
Merchant Processing [Member]
Guarantor Obligations [Line Items]
Collateral Held	625
Carrying Amount	76
Maximum Potential Future Payments	97,431
Tender Option Bond Program Guarantee [Member]
Guarantor Obligations [Line Items]
Collateral Held	1,403
Maximum Potential Future Payments	1,366
Minimum Revenue Guarantees [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	9
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Carrying Amount	186	$ 184
Maximum Potential Future Payments	$ 901

The current carrying amount of the liability for the freestanding or embedded guarantor's obligations under the guarantee or each group of similar guarantees.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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Period Type:	instant

- 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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Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

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- Definition

Guarantee obligations collateral held.

+ References

No definition available.

+ Details

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Balance Type:	debit
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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