Guarantees and Contingent Liabilities - Summary of Other Guarantees and Contingent Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Standby Letters of Credit [Member]
Guarantor Obligations [Line Items]
Carrying Amount	$ 62
Maximum Potential Future Payments	12,817
Third Party Borrowing Arrangements [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	14
Securities Lending Indemnifications [Member]
Guarantor Obligations [Line Items]
Collateral Held	6,454
Maximum Potential Future Payments	6,318
Asset Sales [Member]
Guarantor Obligations [Line Items]
Carrying Amount	114
Maximum Potential Future Payments	5,136
Merchant Processing [Member]
Guarantor Obligations [Line Items]
Collateral Held	521
Carrying Amount	74
Maximum Potential Future Payments	95,567
Contingent Consideration Arrangements [Member]
Guarantor Obligations [Line Items]
Carrying Amount	1
Maximum Potential Future Payments	1
Tender Option Bond Program Guarantee [Member]
Guarantor Obligations [Line Items]
Collateral Held	2,012
Maximum Potential Future Payments	1,957
Minimum Revenue Guarantees [Member]
Guarantor Obligations [Line Items]
Maximum Potential Future Payments	9
Other Guarantees [Member]
Guarantor Obligations [Line Items]
Carrying Amount	189	$ 184
Maximum Potential Future Payments	$ 852

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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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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