Fair Value Option - Components of Gain (Loss) on Debt Designated at Fair Value and Related Derivatives (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ (147)	$ 495	$ (517)	$ 562
Mark-to-market on the related derivatives	(36)	146	(198)	(28)
Net realized gains on the related derivatives	88	151	316	474
Gain (loss) on debt designated at fair value and related derivatives	(95)	792	(399)	1,008
Foreign currency translation gains (losses) recorded in derivative related income (expense) associated with debt designated at fair value	(53)	241	31	(51)
Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives	53	(241)	(31)	51
Interest rate component [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	3	(184)	94	(52)
Credit risk contract [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ (150)	$ 679	$ (611)	$ 614