Allowance for Credit Losses (Analysis of the Allowance for Credit Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Provision for credit losses	$ 244	$ 250	$ 805	$ 918
Allowance for loan and lease losses	2,051		2,051		2,256
Commercial and Industrial [Member]
Allowance for credit losses, Beginning balance	525	474	433	621
Loans and leases charged-off	(84)	(102)	(239)	(242)
Recoveries of previous charge-offs	4	9	12	22
Provision for credit losses	96	55	335	35
Allowance for credit losses, Ending balance	541	436	541	436
Allowance for loan and lease losses	541		541		433
Commercial Real Estate - Other [Member]
Allowance for credit losses, Beginning balance	305	462	334	446
Loans and leases charged-off	(40)	(64)	(164)	(213)
Recoveries of previous charge-offs	3	6	9	15
Provision for credit losses	(30)	26	59	182
Allowance for credit losses, Ending balance	238	430	238	430
Allowance for loan and lease losses	238		238		334
Commercial Real Estate - Residential ADC [Member]
Allowance for credit losses, Beginning balance	157	382	286	469
Loans and leases charged-off	(35)	(61)	(163)	(210)
Recoveries of previous charge-offs	2	9	33	20
Provision for credit losses	(23)	(2)	(55)	49
Allowance for credit losses, Ending balance	101	328	101	328
Allowance for loan and lease losses	101		101		286
Commercial Other Lending Subsidiaries [Member]
Allowance for credit losses, Beginning balance	13	13	11	21
Loans and leases charged-off	(1)	(2)	(7)	(6)
Recoveries of previous charge-offs	1	1	2	3
Provision for credit losses	1	1	8	(5)
Allowance for credit losses, Ending balance	14	13	14	13
Allowance for loan and lease losses	14		14		11
Direct Retail Lending [Member]
Allowance for credit losses, Beginning balance	283	233	232	246
Loans and leases charged-off	(57)	(74)	(170)	(218)
Recoveries of previous charge-offs	9	10	27	27
Provision for credit losses	46	51	192	165
Allowance for credit losses, Ending balance	281	220	281	220
Allowance for loan and lease losses	281		281		232
Retail Revolving Credit [Member]
Allowance for credit losses, Beginning balance	90	103	112	109
Loans and leases charged-off	(20)	(23)	(62)	(74)
Recoveries of previous charge-offs	5	4	14	14
Provision for credit losses	24	21	35	56
Allowance for credit losses, Ending balance	99	105	99	105
Allowance for loan and lease losses	99		99		112
Retail Residential Mortgage [Member]
Allowance for credit losses, Beginning balance	309	347	365	298
Loans and leases charged-off	(35)	(41)	(107)	(224)
Recoveries of previous charge-offs	0	1	2	3
Provision for credit losses	25	57	39	287
Allowance for credit losses, Ending balance	299	364	299	364
Allowance for loan and lease losses	299		299		365
Retail Sales Finance [Member]
Allowance for credit losses, Beginning balance	25	42	38	47
Loans and leases charged-off	(5)	(7)	(19)	(24)
Recoveries of previous charge-offs	2	2	7	7
Provision for credit losses	6	2	2	9
Allowance for credit losses, Ending balance	28	39	28	39
Allowance for loan and lease losses	28		28		38
Retail Other Lending Subsidiaries [Member]
Allowance for credit losses, Beginning balance	200	171	186	177
Loans and leases charged-off	(57)	(40)	(158)	(131)
Recoveries of previous charge-offs	5	6	18	17
Provision for credit losses	85	40	187	114
Allowance for credit losses, Ending balance	233	177	233	177
Allowance for loan and lease losses	233		233		186
Covered [Member]
Allowance for credit losses, Beginning balance	139	159	149	144
Loans and leases charged-off	(2)	(53)	(29)	(53)
Recoveries of previous charge-offs	0	0	0	0
Provision for credit losses	0	7	17	22
Allowance for credit losses, Ending balance	137	113	137	113
Allowance for loan and lease losses	137		137		149
Unallocated [Member]
Allowance for credit losses, Beginning balance	80	130	110	130
Loans and leases charged-off	0	0	0	0
Recoveries of previous charge-offs	0	0	0	0
Provision for credit losses	0	0	(30)	0
Allowance for credit losses, Ending balance	80	130	80	130
Allowance for loan and lease losses	80		80		110
Allowance for Loan and Lease Losses [Member]
Allowance for credit losses, Beginning balance	2,126	2,516	2,256	2,708
Loans and leases charged-off	(336)	(467)	(1,118)	(1,395)
Recoveries of previous charge-offs	31	48	124	128
Provision for credit losses	230	258	789	914
Allowance for credit losses, Ending balance	2,051	2,355	2,051	2,355
Reserve For Unfunded Lending Commitments [Member]
Allowance for credit losses, Beginning balance	31	59	29	47
Loans and leases charged-off	0	0	0	0
Recoveries of previous charge-offs	0	0	0	0
Provision for credit losses	14	(8)	16	4
Allowance for credit losses, Ending balance	45	51	45	51
Allowance for Credit Losses [Member]
Allowance for credit losses, Beginning balance	2,157	2,575	2,285	2,755
Loans and leases charged-off	(336)	(467)	(1,118)	(1,395)
Recoveries of previous charge-offs	31	48	124	128
Provision for credit losses	244	250	805	918
Allowance for credit losses, Ending balance	$ 2,096	$ 2,406	$ 2,096	$ 2,406