Loans and ACL (Breakdown of Recorded Investment in Loans Based on the Method for Determining Allowance) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Individually evaluated for impairment	$ 2,624	$ 2,747
Collectively evaluated for impairment	113,001	111,856
Commercial and Industrial, Excluding Covered [Member]
Individually evaluated for impairment	515	631
Collectively evaluated for impairment	37,741	37,664
CRE - Other, Excluding Covered [Member]
Individually evaluated for impairment	252	312
Collectively evaluated for impairment	11,079	11,149
CRE - Residential ADC, Excluding Covered [Member]
Individually evaluated for impairment	73	155
Collectively evaluated for impairment	909	1,106
Commercial Other Lending Subsidiaries, Excluding Covered [Member]
Individually evaluated for impairment	3	3
Collectively evaluated for impairment	4,427	4,135
Direct Retail Lending, Excluding Covered [Member]
Individually evaluated for impairment	220	235
Collectively evaluated for impairment	15,908	15,582
Retail Revolving Credit, Excluding Covered [Member]
Individually evaluated for impairment	51	56
Collectively evaluated for impairment	2,282	2,274
Retail Residential Mortgage, Excluding Covered [Member]
Individually evaluated for impairment	1,271	1,187
Collectively evaluated for impairment	22,766	23,085
Retail Sales Finance, Excluding Covered [Member]
Individually evaluated for impairment	21	22
Collectively evaluated for impairment	9,111	7,714
Retail Other Lending Subsidiaries, Excluding Covered [Member]
Individually evaluated for impairment	218	146
Collectively evaluated for impairment	6,454	5,853
Covered [Member]
Collectively evaluated for impairment	$ 2,324	$ 3,294