Derivatives and Hedging Activities - Derivative Instrument Cash Flow Hedge Earning Recognized by Income Statement Location (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	$ (3)	$ 83
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	42	38
Net Gains (Losses) Recognized in Income (Ineffective Portion)
Other Income [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in Income (Ineffective Portion)
Other Income [Member] | Foreign Exchange [Member] | Net Investment Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	6	(15)
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	(3)
Net Gains (Losses) Recognized in Income (Ineffective Portion)
Interest Income [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	(25)	106
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	52	45
Interest Expense [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	18	(8)
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	(7)	(7)
Investment Banking and Debt Placement Fee [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	(2)
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)