Retirement Benefit Plans - Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Retirement Benefits [Abstract]
Service cost	$ 10	$ 26	$ 31	$ 78
Interest cost	178	175	535	525
Expected return on plan assets	(340)	(355)	(1,021)	(1,066)
Amortization of net loss	119	211	357	634
Settlement cost	69	0	69	0
Net periodic cost	$ 36	$ 57	$ (29)	$ 171