Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 16,905	$ 15,148
Derivatives, Gross Amounts Offset in Statement of Condition	(11,190)	(10,395)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	5,715	4,753
Derivatives, Net Amount	4,780	4,068
Derivatives, Cash collateral and securities netting, cash offset	(1,383)	(2,310)
Derivatives, Cash collateral and securities netting, Cash and Securities Received	(935)	(685)
Derivatives, Cash collateral and securities netting, Net Amount	(2,318)	(2,995)
Resale agreements and securities borrowing, Gross Amounts of Recognized Assets	140,193	179,989
Resale agreements and securities borrowing, Gross Amounts Offset in Statement of Condition	(121,808)	(159,978)
Resale agreements and securities borrowing, Net Amounts of Assets Presented in Statement of Condition	18,385	20,011
Resale agreements and securities borrowing, Cash and Securities Received	(16,160)	(19,572)
Resale agreements and securities borrowing, Net Amount	2,225	439
Total derivatives and other financial instruments, Gross Amounts of Recognized Assets	157,098	195,137
Total derivatives and other financial instruments, Gross Amounts Offset in Statement of Condition	(132,998)	(170,373)
Total derivatives and other financial instruments, Net Amounts of Assets Presented in Statement of Condition	24,100	24,764
Total derivatives and other financial instruments, Cash and Securities Received	(17,095)	(20,257)
Total derivatives and other financial instruments, Net Amount	7,005	4,507
Securities purchased under resale agreements	4,499	1,487
Cash collateral provided for securities borrowing	13,890	18,520
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	16,905	15,140
Derivatives, Gross Amounts Offset in Statement of Condition	(9,807)	(8,081)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	7,098	7,059
Derivatives, Net Amount	7,098	7,059
Derivatives, Cash collateral and securities netting, Cash and Securities Received	0	0
Interest rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	0	8
Derivatives, Gross Amounts Offset in Statement of Condition	0	(4)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	0	4
Derivatives, Net Amount	0	4
Derivatives, Cash collateral and securities netting, Cash and Securities Received	$ 0	$ 0