Derivative Financial Instruments - Fair Value of Derivative Instruments Held For Trading Purposes (Detail) (USD $) In Millions, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ (85,543)	$ (86,546)
Trading assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	98,237	93,768
Trading assets [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	74,031	60,719
Trading assets [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	14,147	15,654
Trading assets [Member] | Equity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	1,070	1,165
Trading assets [Member] | Precious metals contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	771	1,842
Trading assets [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Assets	8,218	14,388
Trading liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	99,205	93,390
Trading liabilities [Member] | Interest rate contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	74,065	61,280
Trading liabilities [Member] | Foreign exchange contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	13,677	15,413
Trading liabilities [Member] | Equity contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,067	1,164
Trading liabilities [Member] | Precious metals contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	1,910	1,248
Trading liabilities [Member] | Credit contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative Liabilities	$ 8,486	$ 14,285