Derivative Instruments- Impact of Derivative Instruments on Balance Sheet (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Asset derivatives fair value	$ 25,691	[1]	$ 27,602	[1]
Asset derivatives fair value, effect of master netting agreements	(20,279)	[2],[3]	(22,311)	[2],[3]
Asset derivatives fair value, fair value after effect of master netting agreements	5,412		5,291
Liability derivatives fair value	25,304	[1]	28,090	[1]
Liability derivatives fair value, effect of master netting agreements	18,742	[3],[4]	20,990	[3],[4]
Liability Derivatives Fair Value, fair value after effect of master netting agreements	6,562		7,100
Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Asset derivatives fair value	1,135	[5]	989	[5]
Liability derivatives fair value	310	[5]	704	[5]
Designated as Hedging Instrument | Interest Rate Contract
Derivatives, Fair Value [Line Items]
Notional value	20,512	[5]	19,679	[5]
Asset derivatives fair value	897	[5]	928	[5]
Liability derivatives fair value	251	[5]	343	[5]
Designated as Hedging Instrument | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Notional value	12,303	[5]	16,805	[5]
Asset derivatives fair value	238	[5]	61	[5]
Liability derivatives fair value	59	[5]	361	[5]
Nondesignated
Derivatives, Fair Value [Line Items]
Asset derivatives fair value	24,556	[6]	26,613	[6]
Liability derivatives fair value	24,994	[6]	27,386	[6]
Nondesignated | Interest Rate Contract
Derivatives, Fair Value [Line Items]
Notional value	824,106	[6]	796,155	[6]
Asset derivatives fair value	19,889	[6]	22,789	[6]
Liability derivatives fair value	20,376	[6]	23,341	[6]
Nondesignated | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Notional value	407,468	[6]	359,204	[6]
Asset derivatives fair value	4,241	[6]	3,513	[6]
Liability derivatives fair value	4,076	[6]	3,632	[6]
Nondesignated | Equity Contract
Derivatives, Fair Value [Line Items]
Notional value	10,976	[6]	11,375	[6]
Asset derivatives fair value	426	[6]	311	[6]
Liability derivatives fair value	541	[6]	413	[6]
Nondesignated | Credit Risk Contract
Derivatives, Fair Value [Line Items]
Notional value	151	[6]	166	[6]
Asset derivatives fair value	0	[6]	0	[6]
Liability derivatives fair value	$ 1	[6]	$ 0	[6]

[1] Fair values are on a gross basis, before consideration of master netting agreements, as required by ASC 815.

[2] Includes the effect of netting agreements and net cash collateral paid. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[3] Master netting agreements are reported net of cash collateral received and paid of $1,709 million and $172 million, respectively, at March 31, 2013, and $1,452 million and $131 million, respectively, at Dec. 31, 2012.

[4] Includes the effect of netting agreements and net cash collateral received. The offset related to the over-the-counter derivatives was allocated to the various types of derivatives based on the net positions.

[5] The fair value of asset derivatives and liability derivatives designated as hedging instruments is recorded as other assets and other liabilities, respectively, on the balance sheet.

[6] The fair value of asset derivatives and liability derivatives not designated as hedging instruments is recorded as trading assets and trading liabilities, respectively, on the balance sheet.