Guarantees - Additional Information (Detail) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended	1 Months Ended
Dec. 31, 2014	Dec. 31, 2013	May 31, 2009
Allowance for unfunded loan commitments and letters of credit	$ 59,000,000	$ 53,000,000
Repurchased mortgage loans	312,000,000	339,000,000
Business Combination, Contingent Consideration, Liability	27,000,000	26,000,000
Standby Letters of Credit
Maximum potential amount obligation	3,000,000,000	3,300,000,000
Allowance for unfunded loan commitments and letters of credit	5,000,000	3,000,000
Mortgage Servicing Rights [Member]
Loss Contingency Accrual, at Carrying Value	25,000,000	21,000,000
Visa Interest [Member]
Visa Share of Claims in Settlement Agreement Amount	4,400,000,000
Third Party Escrow Deposit	450,000,000	1,000,000,000
Third Party Escrow, Current Balance	1,500,000,000
Tax Credit Sales [Member]
Maximum potential amount obligation	19,000,000
Not Designated as Hedging Instrument [Member] \| Derivative Financial Instruments, Liabilities [Member] \| Visa Interest [Member]
Number Of Shares Sold To Selected Financial Institutions			3.2
Residential Mortgage, Loans Held For Sale [Member]
Repurchased mortgage loans	12,000,000	14,000,000
Residential Mortgage, Loans Held For Sale [Member] \| Nonperforming Financing Receivable [Member]
Repurchased mortgage loans	12,000,000	14,000,000
Loans Held For Investment [Member]
Repurchased mortgage loans	300,000,000	325,000,000
Loans Held For Investment [Member] \| Nonperforming Financing Receivable [Member]
Repurchased mortgage loans	$ 29,000,000	$ 54,000,000

Allowance for unfunded loan commitments and letters of credit

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- Definition

Number of shares sold to selected financial institutions.

+ References

No definition available.

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- Definition

The carrying value of outstanding repurchased mortgage loans, exclusive of any allowance for loan losses.

+ References

No definition available.

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- Definition

Third Party Escrow, Current Balance

+ References

No definition available.

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- Definition

Third Party Escrow Deposit

+ References

No definition available.

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- Definition

Visa Share of Claims in Settlement Agreement Amount

+ References

No definition available.

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- Definition

Amount of liability recognized arising from contingent consideration in a business combination.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 25

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6911189&loc=d3e6408-128476

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 30

-Section 35

-Paragraph 1

-Subparagraph b

-URI http://asc.fasb.org/extlink&oid=6911338&loc=d3e6819-128478

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- 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

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- Definition

Amount of loss contingency liability.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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