Trading Assets and Liabilities (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	$ 21,978	$ 16,150
Trading liabilities	3,643	4,879
U.S. Treasury [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	5,368	3,391
US Government agency issued or guaranteed [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	111	122
US Government-sponsored enterprises [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	41	210
Asset-backed securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	208	236
Corporate and foreign bonds [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	10,562	6,180
Equity securities [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	751	12
Precious metals [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	1,889	2,274
Trading liabilities	215	524
Securities sold, not yet purchased [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading liabilities	738	1,722
Derivatives, net [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading assets	3,048	3,725
Derivatives, net [Member]
Debt and Equity Securities, FV-NI [Line Items]
Trading liabilities	$ 2,690	$ 2,633