Loans and ACL (Summary of Loans Collectively Evaluated for Impairment) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Recorded Investment, Collectively evaluated for impairment	$ 116,803	$ 113,405
Related ALLL, Collectively evaluated for impairment	1,270	1,365
Commercial and Industrial, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	39,664	38,042
Related ALLL, Collectively evaluated for impairment	355	382
CRE Income Producing Properties, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	10,505	10,033
Related ALLL, Collectively evaluated for impairment	156	128
CRE Construction And Development, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	2,656	2,289
Related ALLL, Collectively evaluated for impairment	40	60
Commercial Other Lending Subsidiaries, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	5,253	4,501
Related ALLL, Collectively evaluated for impairment	21	15
Direct Retail Lending, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	7,940	15,648
Related ALLL, Collectively evaluated for impairment	95	166
Retail Revolving Credit, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	2,370	2,355
Related ALLL, Collectively evaluated for impairment	91	96
Retail Residential Mortgage-Nonguaranteed, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	30,262	22,557
Related ALLL, Collectively evaluated for impairment	204	160
Retail Residential Mortgage-Government Guaranteed, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	622	759
Related ALLL, Collectively evaluated for impairment	2	7
Retail Sales Finance, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	10,247	9,363
Related ALLL, Collectively evaluated for impairment	43	41
Retail Other Lending Subsidiaries, Excluding Covered [Member]
Recorded Investment, Collectively evaluated for impairment	5,859	5,823
Related ALLL, Collectively evaluated for impairment	184	196
Covered [Member]
Recorded Investment, Collectively evaluated for impairment	1,425	2,035
Related ALLL, Collectively evaluated for impairment	$ 79	$ 114