Changes in Fair Value of Long-term Debt Included in Foreign Exchange and Other Trading Revenue (Detail) (Long-term Debt, USD $) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2012		Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Long-term Debt
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in fair value under the fair value option election	$ (19)	[1]	$ (11)	[1]	$ (13)	[1]	$ (10)	[1]

[1] The change in fair value of the long-term debt is approximately offset by an economic hedge included in trading.