Loans and Allowance for Credit Losses, Troubled Debt Restructurings Modifications by Type (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Primary Modification Type [Abstract]
Principal	$ 332	$ 561
Interest rate reduction	522	1,089
Other interest rate concessions	1,829	2,546
Total	2,683	4,196
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	85	95
Weighted average interest rate reduction	3.76%	4.03%
Recorded investment related to interest rate reduction	783	1,467
Commercial and Industrial Loans [Member]
Primary Modification Type [Abstract]
Principal	1	50
Interest rate reduction	8	44
Other interest rate concessions	401	611
Total	410	705
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	3	20
Weighted average interest rate reduction	1.28%	3.74%
Recorded investment related to interest rate reduction	9	42
Commercial Real Estate Mortgage [Member]
Primary Modification Type [Abstract]
Principal	4	43
Interest rate reduction	52	57
Other interest rate concessions	485	487
Total	541	587
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	1
Weighted average interest rate reduction	1.90%	1.54%
Recorded investment related to interest rate reduction	53	58
Commercial Real Estate Construction [Member]
Primary Modification Type [Abstract]
Principal	0	25
Interest rate reduction	2	20
Other interest rate concessions	107	157
Total	109	202
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	8	6
Weighted average interest rate reduction	1.06%	0.96%
Recorded investment related to interest rate reduction	1	20
Lease Financing [Member]
Primary Modification Type [Abstract]
Principal	0	0
Interest rate reduction	0	0
Other interest rate concessions	1	18
Total	1	18
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0
Weighted average interest rate reduction	0.00%	0.00%
Recorded investment related to interest rate reduction	0	0
Foreign Loans [Member]
Primary Modification Type [Abstract]
Principal	0	0
Interest rate reduction	0	0
Other interest rate concessions	2	0
Total	2	0
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0
Weighted average interest rate reduction	0.00%	0.00%
Recorded investment related to interest rate reduction	0	0
Total Commercial [Member]
Primary Modification Type [Abstract]
Principal	5	118
Interest rate reduction	62	121
Other interest rate concessions	996	1,273
Total	1,063	1,512
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	11	27
Weighted average interest rate reduction	1.79%	2.21%
Recorded investment related to interest rate reduction	63	120
Real estate 1-4 family first mortgage [Member]
Primary Modification Type [Abstract]
Principal	306	383
Interest rate reduction	297	584
Other interest rate concessions	199	267
Total	802	1,234
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	59	50
Weighted average interest rate reduction	2.83%	3.47%
Recorded investment related to interest rate reduction	540	937
Real estate 1-4 family junior lien mortgage [Member]
Primary Modification Type [Abstract]
Principal	19	40
Interest rate reduction	70	239
Other interest rate concessions	34	61
Total	123	340
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	9	10
Weighted average interest rate reduction	4.02%	4.41%
Recorded investment related to interest rate reduction	86	277
Credit Card [Member]
Primary Modification Type [Abstract]
Principal	0	0
Interest rate reduction	74	109
Other interest rate concessions	0	0
Total	74	109
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	1
Weighted average interest rate reduction	10.88%	10.91%
Recorded investment related to interest rate reduction	74	78
Other revolving credit and installment [Member]
Primary Modification Type [Abstract]
Principal	2	20
Interest rate reduction	19	36
Other interest rate concessions	23	1
Total	44	57
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	6	7
Weighted average interest rate reduction	7.51%	5.89%
Recorded investment related to interest rate reduction	20	55
Trial modifications [Member]
Primary Modification Type [Abstract]
Principal	0	0
Interest rate reduction	0	0
Other interest rate concessions	577	944
Total	577	944
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	0	0
Weighted average interest rate reduction	0.00%	0.00%
Recorded investment related to interest rate reduction	0	0
Total Consumer [Member]
Primary Modification Type [Abstract]
Principal	327	443
Interest rate reduction	460	968
Other interest rate concessions	833	1,273
Total	1,620	2,684
Financial effects of modifications [Abstract]
Charge-offs, financial effects of modifications	74	68
Weighted average interest rate reduction	3.93%	4.19%
Recorded investment related to interest rate reduction	$ 720	$ 1,347

Loans and Allowance for Credit Losses, Troubled Debt Restructurings Modifications by Type (Details) (USD $)
In Millions, unless otherwise specified

3 Months Ended

Mar. 31, 2012

Mar. 31, 2011

Primary Modification Type [Abstract]

Principal

$ 332

$ 561

Interest rate reduction

522

1,089

Other interest rate concessions