Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Sep. 30, 2022
Leases
Finance lease assets (included in Property, plant and equipment, net)	$ 5,230	$ 5,643
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization	Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, after Accumulated Depreciation and Amortization
Operating ROU lease assets (included in Other assets)	$ 1,067	$ 1,085
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Prepaid Expenses and Deferred Costs, Noncurrent	Prepaid Expenses and Deferred Costs, Noncurrent
Finance lease liabilities
Accrued expenses	$ 302	$ 265
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current	Accrued Liabilities, Current
Long-term obligations (less current portion)	$ 6,816	$ 7,119
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Capital Leases Future Minimum Payments And Accrual For Environmental Loss Contingencies Noncurrent	Capital Leases Future Minimum Payments And Accrual For Environmental Loss Contingencies Noncurrent
Total Finance lease liabilities	$ 7,118	$ 7,384
Operating lease liabilities
Operating lease liabilities	$ 1,067	$ 1,085
Weighted average lease term Finance leases	12 years 1 month 6 days	13 years 1 month 6 days
Weighted average lease term Operating leases	2 years	3 years
Weighted average discount rate Finance leases (as a percent)	10.32%	10.32%
Weighted average discount rate Operating leases (as a percent)	5.84%	5.25%