Fair Value Measurements - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013 hedge_fund		Jun. 30, 2012		Jun. 30, 2013 hedge_fund		Jun. 30, 2012		Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2012		Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	$ 27,448				$ 27,448						$ 35,995
Trading liabilities	15,337				15,337						19,820
Fair value assets	2,615		4,006		2,615		4,006		3,181		3,690		3,884		4,157
Derivative, number of instruments held	30				30
Transfers Into Level 3	0		(1)		(46)		(4)
Long-term debt from Level 3 to Level 2	344		314		425		488
Deferred fee on stand by letters of credit	45				45						46
Derivatives [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading securities	9,001				9,001						10,504
Trading liabilities	10,301				10,301						13,846
Deposits In Domestic Office [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Long-term debt from Level 3 to Level 2	208		313		287		475
Long-term Debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets			0	[1]			0	[1]							11	[2]
Transfers Into Level 3	177				160		0	[2]
Long-term debt from Level 3 to Level 2	136		1		138		13
Derivative Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets	1,000		2,400		1,000		2,400
Derivative Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets	740		2,200		740		2,200
Credit contracts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value assets	225	[2]	921	[2]	225	[2]	921	[2]	364	[2]	571	[2]	984	[2]	1,353	[2]
Transfers Into Level 3	$ 0	[2]	$ 0	[2]	$ 46	[2]	$ 0	[2]
Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount					60.00%
Implied volatility percentage					40.00%
Implied volatility					49.00%
Foreign currency correlations					60.00%
Maximum [Member] | Loss Severity Rates [Member] | Residential Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range of Inputs					22.00%
Minimum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Discount					50.00%
Implied volatility percentage					1.00%
Implied volatility					12.00%
Foreign currency correlations					51.00%
Minimum [Member] | Loss Severity Rates [Member] | Residential Mortgage [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range of Inputs					59.00%

[1] Includes Level 3 corporate lending activities risk-managed on a fair value basis for which we have elected the fair value option.

[2] Level 3 net derivatives included derivative assets of $1.0 billion and derivative liabilities of $740 million as of June 30, 2013 and derivative assets of $2.4 billion and derivative liabilities of $2.2 billion as of June 30, 2012.