Trading Assets and Liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	$ 32,650	$ 16,150
Trading liabilities	3,330	4,879
U.S. Treasury [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	4,643	3,391
US Government agency issued or guaranteed [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	117	122
US Government sponsored enterprises [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	7	210
Asset backed securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	240	236
Corporate and foreign bonds [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	8,213	6,180
Other securities [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	0	12
Precious metals [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	16,057	2,274
Trading liabilities	0	524
Securities sold, not yet purchased [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading liabilities	1,627	1,722
Derivatives [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading assets	3,373	3,725
Derivatives [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Trading liabilities	$ 1,703	$ 2,633