Capitalization and Short-Term Borrowings - Schedule of Share-Based Compensation for Stock Appreciation Rights (Details) - Stock Appreciation Rights (SARs) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Number of Shares Subject To Option
Outstanding, beginning of year (in shares)	72,008
Granted (in shares)	0	0	0
Exercised (in shares)	(72,008)		0
Forfeited (in shares)	0
Expired (in shares)	0
Outstanding, end of year (in shares)	0	72,008
SARs exercisable (in shares)	0
Weighted Average Exercise Price
Outstanding, beginning of year (in dollars per share)	$ 53.05
Granted (in dollars per share)	0
Exercised (in dollars per share)	53.05
Forfeited (in dollars per share)	0
Expired (in dollars per share)	0
Outstanding, end of year (in dollars per share)	0	$ 53.05
SARs exercisable (in dollars per share)	$ 0
Aggregate Intrinsic Value
Outstanding, end of year	$ 0
SARs exercisable	$ 0