CONDENSED CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Unaudited) (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2025	Sep. 30, 2025
Trading assets	$ 1,530	$ 1,538
Available-for-sale securities, fair value	6,648	6,888
Other investments	$ 398	$ 390
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	650,000,000	650,000,000
Common stock, shares issued (in shares)	250,084,168	250,084,168
Common stock, shares outstanding (in shares)	197,032,070	198,139,594
Treasury stock (in shares)	53,052,098	51,944,574
Asset pledged as collateral
Trading assets	$ 1,256	$ 1,248
Available-for-sale securities, fair value	8	9
Other investments	$ 23	$ 8