Restricted Cash and Other Restricted Assets (Details) - USD ($) $ in Billions	Jun. 30, 2019	Dec. 31, 2018
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 45.5	$ 40.8
Cash and securities pledged with clearing organizations for the benefit of customers	21.0	20.6
Fair value of securities restricted in relation to customer activity	3.9	9.7
Deposits with banks
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	44.2	39.6
Cash and due from banks
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	1.3	1.2
Cash reserves – Federal Reserve Banks
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	24.9	22.1
Segregated for the benefit of securities and futures brokerage customers
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	16.7	14.6
Cash reserves at non-U.S. central banks and held for other general purposes
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash	$ 3.9	$ 4.1