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, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Mark-to-market on debt designated at fair value :
Interest rate component	$ 57	[1]	$ 48	[1]	$ 121	[1]	$ 253	[1]
Credit risk component	27	[1]	(43)	[1]	2	[1]	(61)	[1]
Total mark-to-market on debt designated at fair value	84	[1]	5	[1]	123	[1]	192	[1]
Mark-to-market on the related derivatives	(78)	[1]	(47)	[1]	(180)	[1]	(267)	[1]
Net realized gains on the related derivatives	66		75		202		243
Gain (loss) on debt designated at fair value and related derivatives	$ 72		$ 33		$ 145		$ 168

[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 $240 million and a loss of $109 million during the three months ended September 30, 2014 and 2013, respectively, and a gain of $255 million and a loss of $28 million for the nine months ended September 30, 2014 and 2013, respectively. Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives was a loss of $240 million and a gain of $109 million during the three months ended September 30, 2014 and 2013, respectively, and a loss of $255 million and a gain of $28 million for the nine months ended September 30, 2014 and 2013, respectively.