Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Retirement Benefits [Abstract]
Service cost	$ 45	$ 6	$ 90	$ 12
Interest cost	271	274	542	549
Expected return on plan assets	(260)	(277)	(521)	(554)
Amortization of net loss	43	77	86	153
Net periodic pension cost	$ 99	$ 80	$ 197	$ 160