Derivatives and Hedging Activities - Pre-Tax Net Gains (Losses) on Fair Value Hedges (Detail) (Fair Value Hedges [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	$ (70)	$ 115
Net Gains (Losses) on Hedged Item	167	1
Other Income [Member] | Interest Rate [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	(167)	(14)
Net Gains (Losses) on Hedged Item	167	8
Other Income [Member] | Foreign Exchange [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative		5
Net Gains (Losses) on Hedged Item		(6)
Interest Expense [Member] | Interest Rate [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative	97	123
Interest Expense [Member] | Foreign Exchange [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) on Derivative		1
Net Gains (Losses) on Hedged Item		$ (1)