Loans and Allowance for Loan Losses (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Reconciliation of changes in the allowance for loan losses by portfolio segments
Loans and Leases Receivable, Allowance, Beginning Balance	$ 704	$ 1,034	$ 764	$ 1,191
(Reversal of) provision for loan losses	(13)	(92)	(12)	(194)
(Reversal of) provision for FDIC covered loan losses not subject to FDIC indemnification	(1)	(2)	(3)	(2)
Decrease in allowance covered by FDIC indemnification	(3)	(3)	(9)	(5)
Loans charged off	44	123	107	196
Recoveries of loans previously charged off	13	12	23	32
Loans and Leases Receivable, Allowance, Ending Balance	656	826	656	826
Commercial [Member]
Reconciliation of changes in the allowance for loan losses by portfolio segments
Loans and Leases Receivable, Allowance, Beginning Balance	439	586	474	683
(Reversal of) provision for loan losses	(38)	(24)	(41)	(92)
Loans charged off	26	99	66	147
Recoveries of loans previously charged off	13	12	21	31
Loans and Leases Receivable, Allowance, Ending Balance	388	475	388	475
Consumer [Member]
Reconciliation of changes in the allowance for loan losses by portfolio segments
Loans and Leases Receivable, Allowance, Beginning Balance	128	174	138	185
(Reversal of) provision for loan losses	14		26	13
Loans charged off	16	23	39	48
Recoveries of loans previously charged off			1	1
Loans and Leases Receivable, Allowance, Ending Balance	126	151	126	151
FDIC Covered [Member]
Reconciliation of changes in the allowance for loan losses by portfolio segments
Loans and Leases Receivable, Allowance, Beginning Balance	10	23	17	25
(Reversal of) provision for FDIC covered loan losses not subject to FDIC indemnification		(2)	(3)	(2)
Decrease in allowance covered by FDIC indemnification		(3)	(9)	(5)
Loans charged off	2	1	2
Recoveries of loans previously charged off			1
Loans and Leases Receivable, Allowance, Ending Balance	4	17	4	17
Unallocated [Member]
Reconciliation of changes in the allowance for loan losses by portfolio segments
Loans and Leases Receivable, Allowance, Beginning Balance	127	251	135	298
(Reversal of) provision for loan losses	11	(68)	3	(115)
Loans and Leases Receivable, Allowance, Ending Balance	$ 138	$ 183	$ 138	$ 183

Reflects the sum for the period of the additions and reductions to the loan loss reserve, which when added to the opening balance of the reserve will agree to the ending balance in the reserve.

+ References+ Details

Reflects the gross amount charged against earnings during the period as credit losses (bad debt expense) based on review of the loan and lease portfolio and application of the methodology for estimating credit losses.

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- Definition

Reflects a reduction in bad debt expense attributable to collections of loans and lease receivables which had previously been fully or partially charged off as bad debts.

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- Definition

Reflects the amount of loans and leases that have been removed, or charged off, from both loan receivables and the reserve for credit losses, typically because they are considered to be not salvageable or have been purchased by unconsolidated collection entities.

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- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 8, 9

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher OTS

-Name Federal Regulation (FR)

-Number Title 12

-Section 563c.102

-Paragraph 8

-Subparagraph a(ii)

-Chapter V

-Subsection I

-LegacyDoc This is a non-GAAP reference that was included in the 2009 taxonomy. It will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 114

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

+ Details