CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2022	Sep. 30, 2021
Assets segregated pursuant to regulations, fair value	$ 2,000	$ 2,100
Trading assets	458	610
Available-for-sale securities	10,464	8,315
Other investments	$ 365	$ 357
Common stock, par value per share (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	650,000,000	350,000,000
Common stock, shares issued (in shares)	247,945,777	239,062,254
Common stock, shares outstanding (in shares)	215,478,025	205,738,821
Treasury stock (in shares)	32,467,752	33,323,433
Asset pledged as collateral
Trading assets	$ 349	$ 326
Available-for-sale securities	51	20
Other investments	$ 22	$ 22