Trading Assets and Liabilities - Trading Assets and Liabilities (Detail) (USD $)	Mar. 31, 2013		Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	$ 34,658,000,000		$ 35,995,000,000
Trading liabilities	19,488,000,000		19,820,000,000
U.S. Treasury [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	1,234,000,000		2,484,000,000
US Government Agencies Debt Securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	330,000,000		337,000,000
US Government sponsored enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	87,000,000	[1]	32,000,000	[1]
Asset backed securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	704,000,000		687,000,000
Corporate and foreign bonds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	8,043,000,000	[2]	9,583,000,000	[2]
Other securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	33,000,000		36,000,000
Precious metals [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	15,875,000,000		12,332,000,000
Trading liabilities	6,186,000,000		5,767,000,000
Derivatives [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	8,352,000,000		10,504,000,000
Trading liabilities	12,461,000,000		13,846,000,000
Securities sold, not yet purchased [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading liabilities	841,000,000		207,000,000
Foreign Bonds, Greece, Italy, Portugal, Spain, Ireland [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	$ 0		$ 0

[1] Includes mortgage backed securities of $19 million and $16 million issued or guaranteed by the Federal National Mortgage Association (“FNMA”) and $69 million and $16 million issued or guaranteed by the Federal Home Loan Mortgage Corporation (“FHLMC”) at March 31, 2013 and December 31, 2012, respectively.

[2] We did not hold any foreign bonds issued by the governments of Greece, Ireland, Italy, Portugal or Spain at either March 31, 2013 or December 31, 2012.