Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Cash and investments segregated and on deposit for regulatory purposes, resale agreements	$ 7,588	$ 9,547
Held to maturity securities	$ 107,446	$ 74,444
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, aggregate liquidation preference (shares)	$ 2,835	$ 2,835
Common stock, shares authorized (shares)	3,000,000,000	3,000,000,000
Common stock, par value (USD per share)	$ 0.01	$ 0.01
Common stock, shares issued (shares)	1,487,543,446	1,487,543,446
Treasury stock (shares)	149,339,521	154,793,560