Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Retirement Benefits [Abstract]
Service cost	$ 6	$ 11	$ 12	$ 21
Interest cost	274	178	549	357
Expected return on plan assets	(277)	(340)	(554)	(681)
Amortization of net loss	77	119	153	238
Net periodic pension cost (benefit)	$ 80	$ (32)	$ 160	$ (65)