Trading Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	$ 33,502	$ 21,978
Trading liabilities	4,026	3,643
U.S. Treasury [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	10,620	5,368
US Government agency issued or guaranteed [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	19	111
US Government-sponsored enterprises [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	59	41
Asset-backed securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	192	208
Corporate and foreign bonds [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	12,925	10,562
Equity securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	2,747	751
Precious metals [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	3,895	1,889
Trading liabilities	106	215
Securities sold, not yet purchased [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading liabilities	834	738
Derivatives, net [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	3,045	3,048
Derivatives, net [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading liabilities	$ 3,086	$ 2,690