Leases - Balance Sheet Information (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Sep. 30, 2019
Leases
Finance lease assets (included in Property, plant and equipment, net)	$ 6,611
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Property, Plant and Equipment, Net
Operating right of use lease assets (included in Other assets)	$ 1,984
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Prepaid Expenses and Deferred Costs, Noncurrent
Finance lease liabilities
Accrued expenses	$ 188
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accrued Liabilities, Current
Long-term obligations (less current portion)	$ 7,665
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Capital Leases Future Minimum Payments And Accrual For Environmental Loss Contingencies Noncurrent
Total Finance lease liabilities	$ 7,853	$ 7,979
Operating lease liabilities
Operating lease liabilities	$ 1,984	$ 4,852
Weighted average lease term Finance leases	15 years 4 months 24 days
Weighted average lease term Operating leases	3 years 2 months 12 days
Weighted average discount rate Finance leases (as a percent)	10.33%
Weighted average discount rate Operating leases (as a percent)	5.25%