Securities - Impairment (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	$ 53,865	$ 83,040
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	619	1,435
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	30,316	42,155
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	745	1,528
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	84,181	125,195
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	1,364	2,963
Equity securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	4	338
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	4	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	4	338
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	4	2
Debt Securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	53,861	82,702
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	615	1,433
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	30,316	42,155
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	745	1,528
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	84,177	124,857
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	1,360	2,961
Mortgage-backed securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	9,967	34,710
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	121	333
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	16,017	26,146
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	341	627
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	25,984	60,856
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	462	960
U.S. government agencies [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	315	2,724
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	2,348	0
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	1	0
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	2,663	2,724
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2	2
Commercial mortgage
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	384	837
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	4	53
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	384	837
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	4	53
Prime and Alt A [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	283	649
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	4	12
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	1,129	970
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	179	206
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	1,412	1,619
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	183	218
Subprime [Member]
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
Non-U.S. [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	8,985	30,500
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	112	266
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	12,540	25,176
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	161	421
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	21,525	55,676
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	273	687
U.S. Treasury and government agencies [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	7,333	3,369
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	5	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	7,333	3,369
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	5	2
Obligations of U.S. states and municipalities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	2,155	147
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	34	42
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	0	40
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	0	6
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	2,155	187
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	34	48
Certificates of Deposit [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	1,430	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	1,430	0
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	2	0
Non-U.S. government debt securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	8,131	11,901
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	52	66
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	499	1,286
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	1	15
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	8,630	13,187
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	53	81
Corporate Debt Securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	16,259	22,230
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	333	901
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	8,602	9,585
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	285	746
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	24,861	31,815
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	618	1,647
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	5,659	5,610
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	54	49
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	4,181	3,913
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	100	117
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	9,840	9,523
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	154	166
Other, Debt Securities [Member]
Fair value and gross unrealized loss, securities impairment [Abstract]
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Fair Value	2,927	4,735
Available-for-sale Securities, with gross unrealized losses, Less than 12 Months, Gross unrealized losses	14	40
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Fair Value	1,017	1,185
Available-for-sale Securities, with gross unrealized losses, 12 Months or Longer, Gross unrealized losses	18	17
Available-for-sale securities, with gross unrealized losses, Fair Value, Total	3,944	5,920
Available-for-sale Securities, with gross unrealized losses, Gross Unrealized Losses	$ 32	$ 57