Loans and ACL (Commercial Credit Exposure Credit Risk Profile by Internal Loan Risk Rating) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Loans and leases	$ 119,523	$ 115,917
Commercial and Industrial, Excluding Covered [Member]
Loans and leases	40,318	38,508
Commercial and Industrial, Excluding Covered [Member] | Pass Grade Credit [Member]
Loans and leases	38,713	36,804
Commercial and Industrial, Excluding Covered [Member] | Special Mention Grade Credit [Member]
Loans and leases	240	219
Commercial and Industrial, Excluding Covered [Member] | Substandard Performing [Member]
Loans and leases	1,067	1,122
Commercial and Industrial, Excluding Covered [Member] | Nonperforming [Member]
Loans and leases	298	363
CRE Income Producing Properties, Excluding Covered [Member]
Loans and leases	10,438	10,228
CRE Income Producing Properties, Excluding Covered [Member] | Pass Grade Credit [Member]
Loans and leases	9,807	9,528
CRE Income Producing Properties, Excluding Covered [Member] | Special Mention Grade Credit [Member]
Loans and leases	62	52
CRE Income Producing Properties, Excluding Covered [Member] | Substandard Performing [Member]
Loans and leases	485	536
CRE Income Producing Properties, Excluding Covered [Member] | Nonperforming [Member]
Loans and leases	84	112
CRE Construction And Development, Excluding Covered [Member]
Loans and leases	2,634	2,382
CRE Construction And Development, Excluding Covered [Member] | Pass Grade Credit [Member]
Loans and leases	2,456	2,149
CRE Construction And Development, Excluding Covered [Member] | Special Mention Grade Credit [Member]
Loans and leases	4	17
CRE Construction And Development, Excluding Covered [Member] | Substandard Performing [Member]
Loans and leases	136	164
CRE Construction And Development, Excluding Covered [Member] | Nonperforming [Member]
Loans and leases	38	52
Commercial Other Lending Subsidiaries, Excluding Covered [Member]
Loans and leases	4,729	4,502
Commercial Other Lending Subsidiaries, Excluding Covered [Member] | Pass Grade Credit [Member]
Loans and leases	4,693	4,464
Commercial Other Lending Subsidiaries, Excluding Covered [Member] | Special Mention Grade Credit [Member]
Loans and leases	1	8
Commercial Other Lending Subsidiaries, Excluding Covered [Member] | Substandard Performing [Member]
Loans and leases	30	29
Commercial Other Lending Subsidiaries, Excluding Covered [Member] | Nonperforming [Member]
Loans and leases	$ 5	$ 1