Fair Value Option - Components of Gain (Loss) on Debt Designated at Fair Value and Related Derivatives (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ (592)		$ 641		$ (160)
Mark-to-market on the related derivatives	(260)		(81)		112
Net realized gains on the related derivatives	403		604		789
Gain (loss) on debt designated at fair value and related derivatives	(449)		1,164		741
Foreign currency translation gains (losses) recorded in derivative related income (expense) associated with debt designated at fair value	(35)		63		84
Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives	35		(63)		(84)
Interest rate component [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	166	[1]	25	[1]	(269)	[1]
Credit risk contract [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ (758)		$ 616		$ 109

[1] Mark-to-market on debt designated at fair value and related derivatives excludes market value changes due to fluctuations in foreign currency exchange rates. Foreign currency translation gains (losses) recorded in derivative related income (expense) associated with debt designated at fair value was a loss of $35 million, a gain of $63 million and a gain of $84 million during 2012, 2011 and 2010, respectively. Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives was a gain of $35 million, a loss of $63 million and a loss of $84 million during 2012, 2011 and 2010, respectively.