Asset Quality (Financial Impact and TDRs by Concession Type) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012 loans	Sep. 30, 2011 loans	Sep. 30, 2012 loans	Sep. 30, 2011 loans
Financing Receivable, Modifications [Line Items]
Number of Loans	3,813	4,338	11,180	15,197
Pre-TDR Recorded Investment	$ 316	$ 324	$ 806	$ 982
Post-TDR Recorded Investment	282	307	727	916
Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	14	30	37	75
Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	139	182	386	642
Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	129	95	304	199
Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	54	193	232	551
Pre-TDR Recorded Investment	189	120	421	321
Post-TDR Recorded Investment	158	109	349	282
Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	14	30	37	75
Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	50	40	124	121
Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	94	39	188	86
Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	3,759	4,145	10,948	14,646
Pre-TDR Recorded Investment	127	204	385	661
Post-TDR Recorded Investment	124	198	378	634
Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	89	142	262	521
Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	35	56	116	113
Commercial [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	35	174	173	493
Pre-TDR Recorded Investment	112	39	226	96
Post-TDR Recorded Investment	94	37	182	82
Commercial [Member] | Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	9	1	13	11
Commercial [Member] | Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	50	14	81	24
Commercial [Member] | Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	35	22	88	47
Commercial Real Estate [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	17	17	51	56
Pre-TDR Recorded Investment	74	81	174	225
Post-TDR Recorded Investment	64	72	154	200
Commercial Real Estate [Member] | Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	5	29	22	64
Commercial Real Estate [Member] | Total commercial lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment		26	43	97
Commercial Real Estate [Member] | Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	59	17	89	39
Equipment Lease Financing [Member] | Total commercial lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	2	2	8	2
Pre-TDR Recorded Investment	3		21
Post-TDR Recorded Investment			13
Equipment Lease Financing [Member] | Total commercial lending [Member] | Principal Forgiveness [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment			2
Equipment Lease Financing [Member] | Total commercial lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment			11
Home Equity [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	962	817	3,148	3,259
Pre-TDR Recorded Investment	65	64	208	264
Post-TDR Recorded Investment	63	63	205	263
Home Equity [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	53	52	165	240
Home Equity [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	10	11	40	23
Residential Real Estate [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	205	399	587	1,298
Pre-TDR Recorded Investment	40	116	114	316
Post-TDR Recorded Investment	39	112	110	293
Residential Real Estate [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	18	70	47	210
Residential Real Estate [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	21	42	63	83
Credit Card [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	2,435	2,800	6,643	9,786
Pre-TDR Recorded Investment	18	21	49	73
Post-TDR Recorded Investment	17	20	48	70
Credit Card [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	17	20	48	70
Other Consumer [Member] | Total consumer lending [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans	157	129	570	303
Pre-TDR Recorded Investment	4	3	14	8
Post-TDR Recorded Investment	5	3	15	8
Other Consumer [Member] | Total consumer lending [Member] | Rate Reduction [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	1		2	1
Other Consumer [Member] | Total consumer lending [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Post-TDR Recorded Investment	$ 4	$ 3	$ 13	$ 7