Loans and Allowance for Credit Losses, Impaired Loans (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Impaired Loans [Abstract]
Unpaid principal balance	$ 30,244	$ 33,646
Impaired loans	25,408	28,070
Impaired loans with related allowance for credit losses	18,366	21,488
Related allowance for credit losses	3,970	5,009
Total Commercial [Member]
Impaired Loans [Abstract]
Unpaid principal balance	5,238	7,346
Impaired loans	3,759	5,334
Impaired loans with related allowance for credit losses	3,489	4,947
Related allowance for credit losses	884	1,156
Commercial and Industrial Loans [Member]
Impaired Loans [Abstract]
Unpaid principal balance	1,524	2,060
Impaired loans	926	1,311
Impaired loans with related allowance for credit losses	757	1,061
Related allowance for credit losses	240	228
Commercial Real Estate Mortgage [Member]
Impaired Loans [Abstract]
Unpaid principal balance	3,190	4,269
Impaired loans	2,483	3,375
Impaired loans with related allowance for credit losses	2,405	3,264
Related allowance for credit losses	591	819
Commercial Real Estate Construction [Member]
Impaired Loans [Abstract]
Unpaid principal balance	491	946
Impaired loans	331	615
Impaired loans with related allowance for credit losses	308	589
Related allowance for credit losses	45	101
Lease Financing [Member]
Impaired Loans [Abstract]
Unpaid principal balance	33	71
Impaired loans	19	33
Impaired loans with related allowance for credit losses	19	33
Related allowance for credit losses	8	8
Total Consumer [Member]
Impaired Loans [Abstract]
Unpaid principal balance	25,006	26,300
Impaired loans	21,649	22,736
Impaired loans with related allowance for credit losses	14,877	16,541
Related allowance for credit losses	3,086	3,853
Real estate 1-4 family first mortgage [Member]
Impaired Loans [Abstract]
Unpaid principal balance	21,324	22,450
Impaired loans	18,600	19,500
Impaired loans with related allowance for credit losses	12,433	13,896
Related allowance for credit losses	2,322	3,026
Real estate 1-4 family junior lien mortgage [Member]
Impaired Loans [Abstract]
Unpaid principal balance	3,094	3,130
Impaired loans	2,534	2,582
Impaired loans with related allowance for credit losses	2,009	2,092
Related allowance for credit losses	653	681
Credit Card [Member]
Impaired Loans [Abstract]
Unpaid principal balance	338	431
Impaired loans	338	431
Impaired loans with related allowance for credit losses	338	431
Related allowance for credit losses	98	132
Automobile [Member]
Impaired Loans [Abstract]
Unpaid principal balance	190	245
Impaired loans	127	189
Impaired loans with related allowance for credit losses	55	95
Related allowance for credit losses	8	11
Other revolving credit and installment [Member]
Impaired Loans [Abstract]
Unpaid principal balance	60	44
Impaired loans	50	34
Impaired loans with related allowance for credit losses	42	27
Related allowance for credit losses	$ 5	$ 3

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

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

- Details

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

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialRealEstateOtherReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoansAutoFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CreditCardReceivablesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_FinanceLeasesFinancingReceivableMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_FirstMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_SecondMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: