Securities - Impairment (Details 2) (USD $) In Millions, unless otherwise specified	Sep. 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	$ 84,845	$ 37,687
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2,306	104
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	3,108	11,028
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	41	146
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	87,953	48,715
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2,347	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	28,047	2,440
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	901	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	28,047	2,440
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	901	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	2,739	1,159
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	24	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	2,739	1,471
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	24	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	34,271	6,259
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	953	29
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	210	1,122
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	4	29
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	34,481	7,381
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	957	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	8,096	4,198
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	237	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	8,096	4,198
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	237	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	13,538	907
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	932	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	13,538	907
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	932	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	894	741
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	3	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	894	741
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	3	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	8,690	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	510	1,927
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	6	4
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	9,200	16,454
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	68	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	3,092	2,651
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	40	10
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	1,626	5,641
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	19	74
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	4,718	8,292
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	59	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	13,788	6,328
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	71	17
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	762	2,063
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	12	35
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	14,550	8,391
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	83	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	2,476	2,076
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	8	7
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	275
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	2,476	2,351
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	8	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	84,845	37,687
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2,306	104
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	3,108	11,028
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	41	146
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	87,953	48,715
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2,347	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	1,510	218
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	25	2
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	76
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	1
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	1,510	294
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	25	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	170	0
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	2	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	170	0
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2	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	1,805	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	210	734
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	4	23
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	2,015	3,176
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	$ 5	$ 29