Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 13,934	$ 16,399
Derivatives, Gross Amounts Offset in Statement of Condition	(8,894)	(11,210)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	5,040	5,189
Derivatives, Net Amount	4,563	4,969
Derivative asset, collateral, cash offset	(793)	(987)
Derivatives, Cash collateral and securities netting, Cash and Securities Received	(477)	(220)
Derivatives, Cash collateral and securities netting, Net	(1,270)	(1,207)
Resale agreements and securities borrowing, Gross Amounts of Recognized Assets	155,464	116,143
Resale agreements and securities borrowing, Gross Amounts Offset in Statement of Condition	(129,754)	(91,889)
Resale agreements and securities borrowing, Net Amounts of Assets Presented in Statement of Condition	25,710	24,254
Resale agreements and securities borrowing, Cash and Securities Received	(24,595)	(22,872)
Resale agreements and securities borrowing, Net Amount	1,115	1,382
Total derivatives and other financial instruments, Gross Amounts of Recognized Assets	169,398	132,542
Total derivatives and other financial instruments, Gross Amounts Offset in Statement of Condition	(138,648)	(103,099)
Total derivatives and other financial instruments, Net Amounts of Assets Presented in Statement of Condition	30,750	29,443
Total derivatives and other financial instruments, Cash and Securities Received(5)	(25,072)	(23,092)
Total derivatives and other financial instruments, Net Amount	5,678	6,351
Securities purchased under resale agreements	3,041	4,679
Cash collateral provided for securities borrowing	22,670	19,580
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	13,912	16,386
Derivatives, Gross Amounts Offset in Statement of Condition	(8,093)	(10,223)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	5,819	6,163
Derivatives, Net Amount	5,819	6,163
Interest rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	22	13
Derivatives, Gross Amounts Offset in Statement of Condition	(8)	0
Derivatives, Net Amounts of Assets Presented in Statement of Condition	14	13
Derivatives, Net Amount	$ 14	$ 13