Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Sep. 30, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	$ 8,379	$ 11,456
Derivatives, gross amounts offset in statement of condition	(4,876)	(6,679)
Derivative, collateral, cash offset	(929)	(776)
Net Amounts of Assets Presented in Statement of Condition	3,503	4,777
Resale agreements and securities borrowing, gross amounts of recognized assets	62,733	62,522
Resale agreements and securities borrowing, gross amounts offset in statement of condition	(36,580)	(38,997)
Net Amounts of Assets Presented in Statement of Condition	26,153	23,525
Total, gross amounts of recognized assets	71,112	73,978
Total, gross amounts offset in statement of condition	(41,456)	(45,676)
Total, net amounts of assets presented in statement of condition	29,656	28,302
Securities purchased under resale agreements	2,442	3,404
Securities borrowed subject to master netting arrangements	23,711	20,121
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	8,137	11,316
Derivatives, gross amounts offset in statement of condition	(3,936)	(5,896)
Net Amounts of Assets Presented in Statement of Condition	4,201	5,420
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	239	135
Derivatives, gross amounts offset in statement of condition	(8)	(5)
Net Amounts of Assets Presented in Statement of Condition	231	130
Other derivative contracts
Offsetting Assets [Line Items]
Derivatives, gross amounts of recognized assets	3	5
Derivatives, gross amounts offset in statement of condition	(3)	(2)
Net Amounts of Assets Presented in Statement of Condition	$ 0	$ 3