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
	Mar. 31, 2013		Mar. 31, 2012
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ 45		$ (400)
Mark-to-market on the related derivatives	(113)	[1]	(116)	[1]
Net realized gains on the related derivatives	84		120
Gain (loss) on debt designated at fair value and related derivatives	16		(396)
Foreign currency translation gains (losses) recorded in derivative related income (expense) associated with debt designated at fair value	110		(60)
Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives	(110)		60
Interest rate component [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	86	[1]	79	[1]
Credit risk contract [Member]
Mark-to-market on debt designated at fair value :
Total mark-to-market on debt designated at fair value	$ (41)		$ (479)

[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 gain of $110 million and a loss of $60 million during the three months ended March 31, 2013 and 2012, respectively. Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives was a loss of $110 million and a gain of $60 million during the three months ended March 31, 2013 and 2012, respectively.