Allowance for Credit Losses (Breakdown of Allowance for Loan and Lease Losses Based on Method for Determining Allowance) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Individually Evaluated For Impairment	$ 366	$ 432
Collectively Evaluated For Impairment	1,597	1,711
Loans Acquired With Deteriorated Credit Quality	88	113
Loans and Leases Receivable, Allowance, Total	2,051	2,256
Commercial and Industrial [Member]
Individually Evaluated For Impairment	76	77
Collectively Evaluated For Impairment	465	356
Loans and Leases Receivable, Allowance, Total	541	433
Commercial Real Estate - Other [Member]
Individually Evaluated For Impairment	42	69
Collectively Evaluated For Impairment	196	265
Loans and Leases Receivable, Allowance, Total	238	334
Commercial Real Estate - Residential ADC [Member]
Individually Evaluated For Impairment	27	50
Collectively Evaluated For Impairment	74	236
Loans and Leases Receivable, Allowance, Total	101	286
Commercial Other Lending Subsidiaries [Member]
Individually Evaluated For Impairment	1	1
Collectively Evaluated For Impairment	13	10
Loans and Leases Receivable, Allowance, Total	14	11
Direct Retail Lending [Member]
Individually Evaluated For Impairment	31	35
Collectively Evaluated For Impairment	250	197
Loans and Leases Receivable, Allowance, Total	281	232
Retail Revolving Credit [Member]
Individually Evaluated For Impairment	25	27
Collectively Evaluated For Impairment	74	85
Loans and Leases Receivable, Allowance, Total	99	112
Retail Residential Mortgage [Member]
Individually Evaluated For Impairment	121	152
Collectively Evaluated For Impairment	178	213
Loans and Leases Receivable, Allowance, Total	299	365
Retail Sales Finance [Member]
Individually Evaluated For Impairment	1	1
Collectively Evaluated For Impairment	27	37
Loans and Leases Receivable, Allowance, Total	28	38
Retail Other Lending Subsidiaries [Member]
Individually Evaluated For Impairment	42	20
Collectively Evaluated For Impairment	191	166
Loans and Leases Receivable, Allowance, Total	233	186
Covered [Member]
Individually Evaluated For Impairment	0	0
Collectively Evaluated For Impairment	49	36
Loans Acquired With Deteriorated Credit Quality	88	113
Loans and Leases Receivable, Allowance, Total	137	149
Unallocated [Member]
Individually Evaluated For Impairment	0	0
Collectively Evaluated For Impairment	80	110
Loans and Leases Receivable, Allowance, Total	$ 80	$ 110