Loans and Leases (Impaired Loans) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012	Dec. 31, 2011
Institutional [Member]
Financing Receivable, Impaired [Line Items]
Additional allowance for loan losses	$ 22	$ 22
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	211	243
Interest Revenue Recognized	16	16
Impaired Financing Receivable, Recorded Investment	197	238
Unpaid Principal Balance	322	367
CRE - Property Development [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivalbe, with No Related Allowance, Recorded Investment	197	199
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	224	227
CRE - Property Development - Acquired Credit Impaired [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivalbe, with No Related Allowance, Recorded Investment	0	0
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	34	34
CRE - Other - Acquired Credit Impaired [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Impaired Financing Receivalbe, with No Related Allowance, Recorded Investment	0	8
Impaired Financing Receivable, with Related Allowance, Recorded Investment	0	31
Impaired Financing Receivable, with No Related Allowance, Unpaid Principal Balance	64	69
Impaired Financing Receivable, with Related Allowance, Unpaid Principal Balance	0	37
With No Related Allowance Recorded [Member] \| CRE - Property Development [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	198	200
Interest Revenue Recognized	16	15
With No Related Allowance Recorded [Member] \| CRE - Other - Acquired Credit Impaired [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	13	12
Interest Revenue Recognized	0	0
With Allowance Recorded [Member] \| CRE - Other - Acquired Credit Impaired [Member] \| Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	0	31
Interest Revenue Recognized	$ 0	$ 1

The balance of financing receivables that were collectively evaluated for impairment.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (h)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=SL6953423-111524

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- Definition

Average amount of investment of impaired financing receivables with related allowance for credit losses and without a 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 (c)(1)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5212-111524

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 17

-URI http://asc.fasb.org/extlink&oid=7512638&loc=d3e5258-111524

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- Definition

Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

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- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a 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 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=7512638&loc=SL6953550-111524

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- Definition

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

+ References

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- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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

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- Definition

Unpaid principal balance of impaired financing receivables for which there is a related allowance for credit losses.

+ References

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