Short-Term and Other Borrowings - Schedule of Short-Term Borrowings (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Debt Disclosure [Abstract]
Balance at year-end	$ 280,000	$ 374,652
Maximum amount outstanding at any month-end	467,917	464,041
Average balance outstanding during the year	$ 364,536	$ 305,623
Weighted-average interest rate:
As of year-end	5.40%	5.56%
Paid during the year	3.11%	2.14%