Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Service cost	$ 17	$ 6
Interest cost	271	274
Expected return on plan assets	(262)	(277)
Amortization of net loss	43	78
Net periodic pension cost (benefit)	$ 69	$ 81