Allowance for Credit Losses (Breakdown of Recorded Investment in Loans Based on the Method for Determining Allowance) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Individually Evaluated for Impairment	$ 2,585	$ 2,809
Collectively Evaluated for Impairment	109,990	102,536
Loans Acquired With Deteriorated Credit Quality	1,565	2,124
Total loans and leases held for investment	114,140	107,469
Commercial and Industrial [Member]
Individually Evaluated for Impairment	667	656
Collectively Evaluated for Impairment	37,345	35,759
Total loans and leases held for investment	38,012	36,415
Commercial Real Estate - Other [Member]
Individually Evaluated for Impairment	366	511
Collectively Evaluated for Impairment	10,547	10,178
Total loans and leases held for investment	10,913	10,689
Commercial Real Estate - Residential ADC [Member]
Individually Evaluated for Impairment	233	420
Collectively Evaluated for Impairment	1,221	1,641
Total loans and leases held for investment	1,454	2,061
Commercial Other Lending Subsidiaries [Member]
Individually Evaluated for Impairment	4	5
Collectively Evaluated for Impairment	4,111	3,621
Total loans and leases held for investment	4,115	3,626
Direct Retail Lending [Member]
Individually Evaluated for Impairment	158	165
Collectively Evaluated for Impairment	15,551	14,339
Loans Acquired With Deteriorated Credit Quality	1	2
Total loans and leases held for investment	15,710	14,506
Retail Revolving Credit [Member]
Individually Evaluated for Impairment	58	62
Collectively Evaluated for Impairment	2,233	2,150
Total loans and leases held for investment	2,291	2,212
Retail Residential Mortgage [Member]
Individually Evaluated for Impairment	1,004	931
Collectively Evaluated for Impairment	23,289	19,650
Total loans and leases held for investment	24,293	20,581
Retail Sales Finance [Member]
Individually Evaluated for Impairment	11	10
Collectively Evaluated for Impairment	7,712	7,391
Total loans and leases held for investment	7,723	7,401
Retail Other Lending Subsidiaries [Member]
Individually Evaluated for Impairment	84	49
Collectively Evaluated for Impairment	5,857	5,062
Total loans and leases held for investment	5,941	5,111
Covered [Member]
Individually Evaluated for Impairment	0	0
Collectively Evaluated for Impairment	2,124	2,745
Loans Acquired With Deteriorated Credit Quality	1,564	2,122
Total loans and leases held for investment	$ 3,688	$ 4,867