Loans and ACL (Breakdown of Recorded Investment in Loans Based on the Method for Determining Allowance) (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Individually Evaluated for Impairment	$ 2,660	$ 2,747
Collectively Evaluated for Impairment	113,134	111,856
Commercial and Industrial [Member]
Individually Evaluated for Impairment	545	631
Collectively Evaluated for Impairment	38,156	37,664
Commercial Real Estate - Other [Member]
Individually Evaluated for Impairment	278	312
Collectively Evaluated for Impairment	11,162	11,149
Commercial Real Estate - Residential ADC [Member]
Individually Evaluated for Impairment	94	155
Collectively Evaluated for Impairment	964	1,106
Commercial Other Lending Subsidiaries [Member]
Individually Evaluated for Impairment	3	3
Collectively Evaluated for Impairment	4,388	4,135
Direct Retail Lending [Member]
Individually Evaluated for Impairment	225	235
Collectively Evaluated for Impairment	15,844	15,582
Retail Revolving Credit [Member]
Individually Evaluated for Impairment	53	56
Collectively Evaluated for Impairment	2,272	2,274
Retail Residential Mortgage [Member]
Individually Evaluated for Impairment	1,239	1,187
Collectively Evaluated for Impairment	22,556	23,085
Retail Sales Finance [Member]
Individually Evaluated for Impairment	21	22
Collectively Evaluated for Impairment	8,800	7,714
Retail Other Lending Subsidiaries [Member]
Individually Evaluated for Impairment	202	146
Collectively Evaluated for Impairment	6,243	5,853
Covered [Member]
Collectively Evaluated for Impairment	$ 2,749	$ 3,294