Loans and Allowance for Loan Losses (Details 6) - USD ($) $ in Millions	Sep. 30, 2015	Dec. 31, 2014
Aging of loans
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	$ 4	$ 3
Loans covered under a loss share agreement with FDIC	22	126
Commercial Loan
Aging of loans
Loans covered under a loss share agreement with FDIC	1	98
Total loans	45,156	44,066
Commercial portfolio
Aging of loans
Total loans	45,020	43,863
Commercial portfolio \| Commercial and industrial
Aging of loans
Total loans	29,110	28,283
Commercial portfolio \| Construction
Aging of loans
Total loans	2,121	1,747
Commercial portfolio \| Commercial mortgage
Aging of loans
Total loans	13,789	13,833
Purchased credit-impaired loans
Aging of loans
Financing Receivable, Recorded Investment, 90 Days Past Due and Still Accruing	30	47
Purchased credit-impaired loans \| Commercial Loan
Aging of loans
Total loans	136	203
Pass \| Commercial Loan
Aging of loans
Total loans	43,413	42,759
Pass \| Commercial portfolio
Aging of loans
Total loans	43,378	42,722
Pass \| Commercial portfolio \| Commercial and industrial
Aging of loans
Total loans	27,768	27,471
Pass \| Commercial portfolio \| Construction
Aging of loans
Total loans	2,115	1,729
Pass \| Commercial portfolio \| Commercial mortgage
Aging of loans
Total loans	13,495	13,522
Pass \| Purchased credit-impaired loans \| Commercial Loan
Aging of loans
Total loans	35	37
Special Mention \| Commercial Loan
Aging of loans
Total loans	824	636
Special Mention \| Commercial portfolio
Aging of loans
Total loans	805	598
Special Mention \| Commercial portfolio \| Commercial and industrial
Aging of loans
Total loans	667	452
Special Mention \| Commercial portfolio \| Construction
Aging of loans
Total loans	6	18
Special Mention \| Commercial portfolio \| Commercial mortgage
Aging of loans
Total loans	132	128
Special Mention \| Purchased credit-impaired loans \| Commercial Loan
Aging of loans
Total loans	19	38
Classified \| Commercial Loan
Aging of loans
Total loans	919	671
Classified \| Commercial portfolio
Aging of loans
Total loans	837	543
Classified \| Commercial portfolio \| Commercial and industrial
Aging of loans
Total loans	675	360
Classified \| Commercial portfolio \| Construction
Aging of loans
Total loans	0	0
Classified \| Commercial portfolio \| Commercial mortgage
Aging of loans
Total loans	162	183
Classified \| Purchased credit-impaired loans \| Commercial Loan
Aging of loans
Total loans	$ 82	$ 128

Amount of unpaid principal balance of financing receivables less charge-offs.

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- Definition

Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 7

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5111-111524

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+ References

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Aggregate gross carrying amount of loans and leases receivable covered by loss sharing agreements.

+ References

No definition available.

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