Derivative Instruments - Credit Derivatives, Protection Sold, Notional and Fair Value (Details 4b) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
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	$ (670,966)	$ (624,697)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(2,217,741)	(2,105,759)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(380,640)	(290,726)
Total notional amount	(3,269,347)	(3,021,182)
Fair value	(11,101)	(20,163)
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	(439,302)	(409,748)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(1,596,456)	(1,383,644)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(297,138)	(224,001)
Total notional amount	(2,332,896)	(2,017,393)
Fair value	(1,267)	(5,703)
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	(231,664)	(214,949)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - from one to five years	(621,285)	(722,115)
Protection sold credit derivatives and credit-related notes ratings/maturity profile - more than five years	(83,502)	(66,725)
Total notional amount	(936,451)	(1,003,789)
Fair value	(9,834)	(14,460)
Trading assets
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	43,910	39,045
Trading assets | Investment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	20,988	16,690
Trading assets | Noninvestment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	22,922	22,355
Trading Liabilities
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	(55,011)	(59,208)
Trading Liabilities | Investment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	(22,255)	(22,393)
Trading Liabilities | Noninvestment-grade
Protection sold credit derivatives and credit related notes ratings/maturity profile
Fair value	$ (32,756)	$ (36,815)