Offsetting Arrangements - Assets With Offsetting Arrangements (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	$ 11,144	$ 16,399
Derivatives, Gross Amounts Offset in Statement of Condition	(6,966)	(11,210)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	4,178	5,189
Derivatives, Net Amount	3,710	4,969
Derivative asset, collateral, cash offset	(639)	(987)
Derivatives, Cash collateral and securities netting, Cash and Securities Received	(468)	(220)
Derivatives, Cash collateral and securities netting, Net	(1,107)	(1,207)
Resale agreements and securities borrowing, Gross Amounts of Recognized Assets	103,293	116,143
Resale agreements and securities borrowing, Gross Amounts Offset in Statement of Condition	(77,842)	(91,889)
Resale agreements and securities borrowing, Net Amounts of Assets Presented in Statement of Condition	25,451	24,254
Resale agreements and securities borrowing, Cash and Securities Received	(24,487)	(22,872)
Resale agreements and securities borrowing, Net Amount	964	1,382
Total derivatives and other financial instruments, Gross Amounts of Recognized Assets	114,437	132,542
Total derivatives and other financial instruments, Gross Amounts Offset in Statement of Condition	(84,808)	(103,099)
Total derivatives and other financial instruments, Net Amounts of Assets Presented in Statement of Condition	29,629	29,443
Total derivatives and other financial instruments, Cash and Securities Received(5)	(24,955)	(23,092)
Total derivatives and other financial instruments, Net Amount	4,674	6,351
Securities purchased under resale agreements	1,522	4,679
Cash collateral provided for securities borrowing	23,930	19,580
Foreign exchange contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets	11,144	16,386
Derivatives, Gross Amounts Offset in Statement of Condition	(6,327)	(10,223)
Derivatives, Net Amounts of Assets Presented in Statement of Condition	4,817	6,163
Derivatives, Net Amount	$ 4,817	6,163
Interest rate contracts
Offsetting Assets [Line Items]
Derivatives, Gross Amounts of Recognized Assets		13
Derivatives, Gross Amounts Offset in Statement of Condition		0
Derivatives, Net Amounts of Assets Presented in Statement of Condition		13
Derivatives, Net Amount		$ 13