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, 2012	Sep. 30, 2011
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	$ 83	$ 21
Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	38	30
Net Gains (Losses) Recognized in Income (Ineffective Portion)
Foreign Exchange [Member] | Net Investment Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	(15)
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] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in Income (Ineffective Portion)
Interest Income [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	45	38
Interest Income [Member] | Interest rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	106	65
Interest Expense [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Reclassified From OCI Into Income (Effective Portion)	(7)	(8)
Interest Expense [Member] | Interest rate [Member] | Cash Flow Hedges [Member]
Derivatives, Fair Value [Line Items]
Net Gains (Losses) Recognized in OCI (Effective Portion)	$ (8)	$ (44)