Loans and ACL (Commercial Credit Exposure Credit Risk Profile by Internal Loan Risk Rating) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Loans and leases	$ 115,794	$ 114,603
Commercial and Industrial [Member]
Loans and leases	38,701	38,295
Commercial and Industrial [Member] | Pass Grade Credit [Member]
Loans and leases	36,714	36,044
Commercial and Industrial [Member] | Special Mention Grade Credit [Member]
Loans and leases	249	274
Commercial and Industrial [Member] | Substandard Performing [Member]
Loans and leases	1,281	1,431
Commercial and Industrial [Member] | Nonperforming [Member]
Loans and leases	457	546
Commercial Real Estate - Other [Member]
Loans and leases	11,440	11,461
Commercial Real Estate - Other [Member] | Pass Grade Credit [Member]
Loans and leases	10,390	10,095
Commercial Real Estate - Other [Member] | Special Mention Grade Credit [Member]
Loans and leases	114	120
Commercial Real Estate - Other [Member] | Substandard Performing [Member]
Loans and leases	755	1,034
Commercial Real Estate - Other [Member] | Nonperforming [Member]
Loans and leases	181	212
Commercial Real Estate - Residential ADC [Member]
Loans and leases	1,058	1,261
Commercial Real Estate - Residential ADC [Member] | Pass Grade Credit [Member]
Loans and leases	810	859
Commercial Real Estate - Residential ADC [Member] | Special Mention Grade Credit [Member]
Loans and leases	16	41
Commercial Real Estate - Residential ADC [Member] | Substandard Performing [Member]
Loans and leases	167	233
Commercial Real Estate - Residential ADC [Member] | Nonperforming [Member]
Loans and leases	65	128
Commercial Other Lending Subsidiaries [Member]
Loans and leases	4,391	4,138
Commercial Other Lending Subsidiaries [Member] | Pass Grade Credit [Member]
Loans and leases	4,351	4,093
Commercial Other Lending Subsidiaries [Member] | Special Mention Grade Credit [Member]
Loans and leases	25	13
Commercial Other Lending Subsidiaries [Member] | Substandard Performing [Member]
Loans and leases	13	29
Commercial Other Lending Subsidiaries [Member] | Nonperforming [Member]
Loans and leases	$ 2	$ 3