CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Statement of Financial Position [Abstract]
Allowance for credit losses on loans	$ 178,069	$ 172,808
Goodwill	$ 303,457	$ 303,457
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	300,000	300,000
Preferred stock, shares outstanding (in shares)	300,000	300,000
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized (in shares)	300,000,000	300,000,000
Common stock, shares issued (in shares)	136,457,717	136,270,886
Common stock, shares outstanding (in shares)	64,721,190	65,330,126
Treasury stock, shares (in shares)	71,736,527	70,940,760