Derivative Instruments - Credit Derivatives, Protection Sold, Notional and Fair Value (Details 4b) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than one year	$ (622,827)	$ (594,038)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(1,925,536)	(1,852,097)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(608,302)	(473,810)
Total notional amount	(3,156,665)	(2,919,945)
Fair value	(91,958)	(143,001)
Noninvestment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than one year	(247,436)	(241,823)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(602,887)	(589,954)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(153,420)	(127,814)
Total notional amount	(1,003,743)	(959,591)
Fair value	(64,394)	(85,304)
Investment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Protection sold credit derivatives and credit related notes ratings/maturity profile - less than one year	(375,391)	(352,215)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(1,322,649)	(1,262,143)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(454,882)	(345,996)
Total notional amount	(2,152,922)	(1,960,354)
Fair value	$ (27,564)	$ (57,697)