Pension and Retirement Plans - Accrued benefit liability (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Liability, Defined Benefit Plan [Abstract]
Non-current benefits assets	$ 1,958	$ 1,099
Current accrued benefit liability	98	110
Non-current accrued benefit liability	1,251	1,337
Total accrued benefit liability	1,349	1,447
Accumulated other comprehensive income	86	$ 358
Pension and Other Postretirement Benefit Plans, Amounts that Will be Amortized from Accumulated Other Comprehensive Income (Loss) in Next Fiscal Year	207
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	$ 200