Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 16,552	$ 11,456
Derivatives, Gross Amounts Offset in Statement of Condition	(9,231)	(6,679)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	7,321	4,777
Derivatives, Net Amount	7,074	4,372
Derivatives, Cash collateral and securities netting, offset	906	776
Derivatives, Cash collateral and securities netting, Cash and Securities Received	(247)	(405)
Derivatives, Cash collateral and securities netting, Net	(1,153)	(1,181)
Resale agreements and securities borrowing, Gross Amounts of Recognized Assets	58,677	62,522
Resale agreements and securities borrowing, Gross Amounts Offset in Statement of Condition	(35,517)	(38,997)
Resale agreements and securities borrowing, Net Amounts of Assets Presented in Statement of Condition	23,160	23,525
Resale agreements and securities borrowing, Cash and Securities Received	(22,939)	(22,875)
Resale agreements and securities borrowing, Net Amount	221	650
Total derivatives and other financial instruments, Gross Amounts of Recognized Assets	75,229	73,978
Total derivatives and other financial instruments, Gross Amounts Offset in Statement of Condition	44,748	45,676
Total derivatives and other financial instruments, Net Amounts of Assets Presented in Statement of Condition	30,481	28,302
Total derivatives and other financial instruments, Cash and Securities Received(5)	(23,186)	(23,280)
Total derivatives and other financial instruments, Net Amount	7,295	5,022
Securities purchased under resale agreements	1,956	3,404
Securities borrowed subject to master netting arrangements	21,204	20,121
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	16,484	11,316
Derivatives, Gross Amounts Offset in Statement of Condition	(8,257)	(5,896)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	8,227	5,420
Derivatives, Net Amount	8,227	5,420
Interest-rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	68	135
Derivatives, Gross Amounts Offset in Statement of Condition	(68)	(5)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	0	130
Derivatives, Net Amount	$ 0	130
Other derivative contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets		5
Derivatives, Gross Amounts Offset in Statement of Condition		(2)
Derivatives, Net Amounts of Assets Presented in Statement of Condition		3
Derivatives, Net Amount		$ 3