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, 2016	Dec. 31, 2015	Dec. 31, 2014
Mark-to-market on debt designated at fair value :
Interest rate component	[1]	$ 75	$ 189	$ 168
Credit risk component	[1]	(10)	42	27
Total mark-to-market on debt designated at fair value	[1]	65	231	195
Mark-to-market on the related derivatives	[1],[2]	(61)	(213)	(254)
Net realized gains on the related derivatives	[1]	48	195	267
Gain on debt designated at fair value and related derivatives		52	213	208
Foreign currency translation gains (losses) recorded in derivatives		27	264	391
Offsetting gains (losses) recorded in derivative related income (expense)		$ (27)	$ (264)	$ (391)

[1] The derivatives associated with debt designated at fair value are economic hedges but do not qualify for hedge accounting. See Note 10, "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 $27 million, a gain of $264 million and a gain of $391 million for the years ended December 31, 2016, 2015 and 2014, respectively. Offsetting gains (losses) recorded in derivative related income (expense) associated with the related derivatives was a loss of $27 million, a loss of $264 million and a loss of $391 million for the years ended December 31, 2016, 2015 and 2014, respectively.