Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Cash and investments segregated and on deposit for regulatory purposes, resale agreements	$ 9,407	$ 9,028
Available-for-sale, amortized cost	$ 273,747	$ 61,155
Preferred stock, par value (USD per share)	$ 0.01	$ 0.01
Preferred stock, aggregate liquidation preference	$ 5,350	$ 2,850
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)	199,058,357	201,818,100

Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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