Securities - Impairment (Details 2) (USD $) In Millions, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	$ 85,596	$ 37,687
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2,326	104
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	2,986	11,028
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	49	146
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	88,582	48,715
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2,375	250
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	34,624	2,440
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	1,117	13
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	34,624	2,440
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	1,117	13
Commercial Mortgage Backed Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	1,776	1,159
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	40	8
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	312
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	5
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	1,776	1,471
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	40	13
Collateralized Mortgage Backed Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	37,783	6,259
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	1,189	29
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	310	1,122
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	8	29
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	38,093	7,381
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	1,197	58
US Treasury and Government
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	14,128	4,198
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	208	8
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	14,128	4,198
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	208	8
US States and Political Subdivisions Debt Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	11,969	907
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	758	10
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	11,969	907
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	758	10
Certificates of Deposit
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	286	741
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	1	2
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	286	741
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	1	2
Foreign Government Debt Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	8,023	14,527
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	62	21
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	1,927
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	4
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	8,023	16,454
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	62	25
Corporate Debt Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	5,267	2,651
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	72	10
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	1,628	5,641
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	27	74
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	6,895	8,292
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	99	84
Collateralized loan obligations
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	6,820	6,328
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	34	17
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	906	2,063
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	13	35
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	7,726	8,391
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	47	52
Other Debt Obligations
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	1,320	2,076
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2	7
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	142	275
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	1	4
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	1,462	2,351
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	3	11
Debt Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	85,596	37,687
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2,326	104
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	2,986	11,028
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	49	146
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	88,582	48,715
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2,375	250
Equity securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	0	0
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	0	0
Residential and commercial mortgage securitizations | Prime and Alt-A
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	1,229	218
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	31	2
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	61	76
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	1	1
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	1,290	294
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	32	3
Residential and commercial mortgage securitizations | Subprime
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	0	0
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	0	0
Residential and commercial mortgage securitizations | Foreign Mortgage-backed Securities
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	154	2,442
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	1	6
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	249	734
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	7	23
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	403	3,176
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	$ 8	$ 29