Offsetting Arrangements (Assets With Offsetting Arrangements) (Details) (USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 10,425	[1]	$ 9,601	[1]
Derivatives, Gross Amounts Offset in Statement of Condition	(6,105)	[2]	(5,045)	[2]
Net Amounts of Assets Presented in Statement of Condition	4,320		4,556
Resale Agreements and Securities Borrowing, Gross Amounts of Recognized Assets	45,563	[1],[3]	35,658	[1],[3]
Resale Agreements and Securities Borrowing, Gross Amounts Offset in Statement of Condition	(29,974)	[2],[3]	(23,809)	[2],[3]
Net Amounts of Assets Presented in Statement of Condition	15,589	[3]	11,849	[3]
Total, Gross Amounts of Recognized Assets	55,988	[1]	45,259	[1]
Total, Gross Amounts Offset in Statement of Condition	(36,079)	[2]	(28,854)	[2]
Total, Net Amounts of Assets Presented in Statement of Condition	19,909		16,405
Securities purchased under resale agreements	5,827		5,016
Securities borrowed subject to master netting arrangements	9,762		6,833
Cash collateral netting
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	0	[1]	0	[1]
Derivatives, Gross Amounts Offset in Statement of Condition	(2,303)	[2]	(1,451)	[2]
Net Amounts of Assets Presented in Statement of Condition	(2,303)		(1,451)
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	58	[1]	223	[1]
Derivatives, Gross Amounts Offset in Statement of Condition	(45)	[2]	(19)	[2]
Net Amounts of Assets Presented in Statement of Condition	13		204
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	10,366	[1]	9,378	[1]
Derivatives, Gross Amounts Offset in Statement of Condition	(3,757)	[2]	(3,575)	[2]
Net Amounts of Assets Presented in Statement of Condition	6,609		5,803
Other derivative contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	1		0
Derivatives, Gross Amounts Offset in Statement of Condition	0		0
Net Amounts of Assets Presented in Statement of Condition	$ 1		$ 0

[1] Amounts include all transactions regardless of whether or not they are subject to an enforceable netting arrangement.

[2] Amounts subject to netting arrangements which have been determined to be legally enforceable.

[3] Included in the $15,589 million as of September 30, 2013 was $5,827 million of resale agreements and $9,762 million of collateral related to securities borrowing. Included in the $11,849 million as of December 31, 2012 was $5,016 million of resale agreements and $6,833 million of collateral related to securities borrowing. Resale agreements and collateral related to securities borrowing were recorded in securities purchased under resale agreements and other assets, respectively, in our consolidated statement of condition. Refer to note 8 for additional information with respect to principal securities finance transactions.