Notional Amounts and Fair Values for All Derivative Instruments Included in the Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Derivatives, Fair Value
Fair value - Derivative Assets	$ 2,126	$ 1,852
Fair value - Derivative Liabilities	967	938
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges
Derivatives, Fair Value
Fair value - Derivative Assets	551	411
Fair value - Derivative Liabilities		2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	453	372
Fair value - Derivative Liabilities		2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Fair Value Hedging \| Interest Rate Swap \| Long-Term Debt
Derivatives, Fair Value
Notional amount	2,705	2,705
Fair value - Derivative Assets	453	372
Fair value - Derivative Liabilities		2
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging
Derivatives, Fair Value
Fair value - Derivative Assets	98	39
Accumulated Net Gain (Loss) from Designated or Qualifying Hedges \| Cash Flow Hedging \| Interest Rate Swap \| Commercial and Industrial Loans
Derivatives, Fair Value
Notional amount	4,475	5,475
Fair value - Derivative Assets	98	39
Nondesignated
Derivatives, Fair Value
Fair value - Derivative Assets	1,575	1,441
Fair value - Derivative Liabilities	967	936
Nondesignated \| Risk Management and Other Business Purposes
Derivatives, Fair Value
Fair value - Derivative Assets	671	504
Fair value - Derivative Liabilities	121	71
Nondesignated \| Risk Management and Other Business Purposes \| Interest Rate Contract \| Servicing Rights
Derivatives, Fair Value
Notional amount	9,407	11,657
Fair value - Derivative Assets	363	239
Fair value - Derivative Liabilities	55	9
Nondesignated \| Risk Management and Other Business Purposes \| Forward Contracts \| Assets Held For Sale
Derivatives, Fair Value
Notional amount	1,423	1,330
Fair value - Derivative Assets		3
Fair value - Derivative Liabilities	8	1
Nondesignated \| Risk Management and Other Business Purposes \| Warrant
Derivatives, Fair Value
Notional amount	420	369
Fair value - Derivative Assets	308	262
Nondesignated \| Risk Management and Other Business Purposes \| Swap
Derivatives, Fair Value
Notional amount	1,274	1,292
Fair value - Derivative Liabilities	55	61
Nondesignated \| Risk Management and Other Business Purposes \| Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	129
Fair value - Derivative Liabilities	3
Nondesignated \| Customer Accommodation
Derivatives, Fair Value
Fair value - Derivative Assets	904	937
Fair value - Derivative Liabilities	846	865
Nondesignated \| Customer Accommodation \| Interest Rate Contract
Derivatives, Fair Value
Notional amount	30,604	29,889
Fair value - Derivative Assets	357	242
Fair value - Derivative Liabilities	366	249
Nondesignated \| Customer Accommodation \| Interest Rate Lock Commitments
Derivatives, Fair Value
Notional amount	1,121	721
Fair value - Derivative Assets	29	15
Nondesignated \| Customer Accommodation \| Commodity Contract
Derivatives, Fair Value
Notional amount	2,248	2,464
Fair value - Derivative Assets	233	294
Fair value - Derivative Liabilities	211	276
Nondesignated \| Customer Accommodation \| Foreign Exchange Contract
Derivatives, Fair Value
Notional amount	15,039	16,243
Fair value - Derivative Assets	285	386
Fair value - Derivative Liabilities	$ 269	$ 340

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=51814546&loc=SL51823488-111719

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=51814546&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=51825145&loc=SL20226000-175313

+ Details

Name:	us-gaap_DerivativeFairValueOfDerivativeLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

Name:	us-gaap_DerivativesFairValueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration