Leases - Reconciliation of future undiscounted cash flows to the operating and finance lease liabilities, and the related ROU assets (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Operating leases
Year1	$ 5,448	$ 5,614
Year 2	4,679	4,985
Year 3	4,032	3,984
Year 4	3,654	2,438
Year 4 and thereafter	20,453	6,984
Total minimum lease payments	38,266	24,005
Less: amounts representing interest	5,691	2,211
Present value of net minimum lease payments	32,575	21,794
Less: current portion of lease obligations	4,543	5,009
Non-current portion of lease obligations	28,032	16,785
ROU assets	31,846	21,390
Finance leases
Year 1	3,153	2,930
Year 2	3,235	3,011
Year 3	3,319	3,094
Year 4	3,399	3,177
Year 4 and thereafter	25,516	28,323
Total minimum lease payments	38,622	40,535
Less: amounts representing interest	9,092	10,270
Present value of net minimum lease payments	29,530	30,265
Less: current portion of lease obligations	2,180	1,937
Non-current portion of lease obligations	27,350	28,328
ROU assets	$ 24,964	$ 26,164
Location of operating lease liabilities included on Consolidated Balance Sheets	Less: current portion of lease obligations, Non-current portion of lease obligations
Finance Lease, Liability, Statement of Financial Position [Extensible List]	Other Accrued Liabilities, Current, Other Liabilities, Noncurrent
Location of operating lease ROU assets included on Consolidated Balance Sheets	ROU assets
Location of finance lease ROU assets included on Consolidated Balance Sheets	Property, Plant and Equipment, Net	Property, Plant and Equipment, Net
Location of operating lease liabilities current included on Consolidated Balance Sheets	Other Accrued Liabilities, Current	Other Accrued Liabilities, Current
Location of finance lease liabilities current included on Consolidated Balance Sheets	Other Accrued Liabilities, Current	Other Accrued Liabilities, Current
Location of finance lease liabilities non-current included on Consolidated Balance Sheets	Other Liabilities, Noncurrent	Other Liabilities, Noncurrent