Derivative Instruments - Credit Derivatives (Details 4a) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Credit Derivatives - supplemental information
Tranche Credit Default Swap Realized Credit Loss Example Protection	$ 1
Tranche Credit Default Swap Example Portfolio of Exposure	10
Total credit derivatives and credit-related notes
Protection sold	(3,021,182)	(2,919,945)
Credit Derivatives, Purchased Credit Protection	2,884,754	2,803,161
Net protection (sold)/purchased	(136,428)	(116,784)
Other protection purchased	78,889	55,375
Total credit derivatives
Total credit derivatives and credit-related notes
Protection sold	(3,020,949)	(2,919,203)
Credit Derivatives, Purchased Credit Protection	2,884,754	2,803,161
Net protection (sold)/purchased	(136,195)	(116,042)
Other protection purchased	75,634	51,431
Credit default swaps
Total credit derivatives and credit-related notes
Protection sold	(2,954,705)	(2,839,492)
Credit Derivatives, Purchased Credit Protection	2,879,105	2,798,207
Net protection (sold)/purchased	(75,600)	(41,285)
Other protection purchased	42,460	29,139
Other credit derivatives
Total credit derivatives and credit-related notes
Protection sold	(66,244)	(79,711)
Credit Derivatives, Purchased Credit Protection	5,649	4,954
Net protection (sold)/purchased	(60,595)	(74,757)
Other protection purchased	33,174	22,292
Credit-related notes
Total credit derivatives and credit-related notes
Protection sold	(233)	(742)
Credit Derivatives, Purchased Credit Protection	0	0
Net protection (sold)/purchased	(233)	(742)
Other protection purchased	$ 3,255	$ 3,944