Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 10,592	$ 15,214
Derivatives, Gross Amounts Offset in Statement of Condition	(5,424)	(7,280)
Net Amounts of Assets Presented in Statement of Condition	5,168	7,934
Derivative, Collateral, Cash Offset	(701)	(983)
Total Net Derivative Asset	5,168	7,934
Resale Agreements and Securities Borrowing, Gross Amounts of Recognized Assets	60,204	47,488
Resale Agreements and Securities Borrowing, Gross Amounts Offset in Statement of Condition	(33,810)	(29,157)
Net Amounts of Assets Presented in Statement of Condition	26,394	18,331
Total, Gross Amounts of Recognized Assets	70,796	62,702
Total, Gross Amounts Offset in Statement of Condition	(39,234)	(36,437)
Total, Net Amounts of Assets Presented in Statement of Condition	31,562	26,265
Securities purchased under resale agreements	4,447	2,390
Securities borrowed subject to master netting arrangements	21,947	15,941
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	10,539	15,135
Derivatives, Gross Amounts Offset in Statement of Condition	(4,698)	(6,275)
Net Amounts of Assets Presented in Statement of Condition	5,841	8,860
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	49	77
Derivatives, Gross Amounts Offset in Statement of Condition	(21)	(21)
Net Amounts of Assets Presented in Statement of Condition	28	56
Equity Derivative Contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	2	0
Derivatives, Gross Amounts Offset in Statement of Condition	(2)	0
Net Amounts of Assets Presented in Statement of Condition	0	0
Other Derivative Contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	2	2
Derivatives, Gross Amounts Offset in Statement of Condition	(2)	(1)
Net Amounts of Assets Presented in Statement of Condition	$ 0	$ 1