Derivatives and Hedging Activities - Derivative Instrument Cash Flow Hedge Earning Recognized by Income Statement Location (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	$ (34)	$ 37
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	28	24
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)	10	(6)
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)	(62)	50
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	35	29
Interest Expense [Member] | Interest Rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	15	(7)
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	(4)	(5)
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)	$ 3