Fair Value Option- 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				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Long-term debt
Fair Value, Option, Quantitative Disclosures [Line Items]
Changes in the fair value of long-term debt	$ 1	[1]	$ (2)	[1]	$ (16)	[1]	$ 19	[1]

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