Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	$ 16,674	$ 11,456
Derivatives, gross amounts offset in statement of condition	(10,861)	(6,679)
Net Amounts of Assets Presented in Statement of Condition	5,813	4,777
Derivative, collateral, cash offset	(3,166)	(776)
Total net derivative asset	5,813	4,777
Resale agreements and securities borrowing, gross amounts of recognized assets	63,868	62,522
Resale agreements and securities borrowing, gross amounts offset in statement of condition	(38,404)	(38,997)
Net Amounts of Assets Presented in Statement of Condition	25,464	23,525
Total, gross amounts of recognized assets	80,542	73,978
Total, gross amounts offset in statement of condition	(49,265)	(45,676)
Total, net amounts of assets presented in statement of condition	31,277	28,302
Securities purchased under resale agreements	3,722	3,404
Securities borrowed subject to master netting arrangements	21,742	20,121
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	16,300	11,316
Derivatives, gross amounts offset in statement of condition	(7,684)	(5,896)
Net Amounts of Assets Presented in Statement of Condition	8,616	5,420
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	371	135
Derivatives, gross amounts offset in statement of condition	(9)	(5)
Net Amounts of Assets Presented in Statement of Condition	362	130
Equity derivative contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	0	1
Derivatives, gross amounts offset in statement of condition	0	0
Net Amounts of Assets Presented in Statement of Condition	0	1
Other derivative contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	3	4
Derivatives, gross amounts offset in statement of condition	(2)	(2)
Net Amounts of Assets Presented in Statement of Condition	$ 1	$ 2