Asset Quality - Changes in Allowance for Loan and Lease Losses by Loan Category (Parenthetical) (Detail) - USD ($) $ in Millions	9 Months Ended
Sep. 30, 2015	Sep. 30, 2014
Receivables [Abstract]
Provision/Credit for losses on lending-related commitments	$ 110	$ 52
Foreign currency translation adjustment	$ 1

Amount of expense related to estimated loss from loan and lease transactions.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.11)

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

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-Section 45

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Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

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Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration