Fair Value Option - Components of Gain (Loss) on Debt Designated at Fair Value and Related Derivatives (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2015		Dec. 31, 2014		Dec. 31, 2013
Mark-to-market on debt designated at fair value :
Interest rate component		$ 189	[1]	$ 168	[1]	$ 314	[2]
Credit risk component		42	[1]	27	[1]	(71)	[2]
Total mark-to-market on debt designated at fair value		231	[1]	195	[1]	243	[2]
Mark-to-market on the related derivatives	[1],[2]	(213)		(254)		(333)
Net realized gains on the related derivatives	[1]	195		267		318
Gain on debt designated at fair value and related derivatives		213		208		228
Foreign currency translation gains (losses) recorded in derivatives		264		391		(73)
Offsetting gains (losses) recorded in derivative related income (expense)		$ (264)		$ (391)		$ 73

[1] The derivatives associated with debt designated at fair value are economic hedges but do not qualify for hedge accounting. See Note 11, "Derivative Financial Instruments," for additional discussion of these non-qualifying hedges.

[2] 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 $264 million, a gain of $391 million and a loss of $73 million for the years ended December 31, 2015, 2014 and 2013, respectively. Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives was a loss of $264 million, a loss of $391 million and a gain of $73 million for the years ended December 31, 2015, 2014 and 2013, respectively.