LEASES - Reconciliation of future undiscounted cash flows to the operating and finance lease liabilities, and the related ROU assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Operating leases
2021 (excluding the three months ended December 31, 2020)	$ 4,182
2022	4,980
2023	3,984
2024	2,438
2025 and thereafter	7,208
Total minimum lease payments	22,792
Less: amounts representing interest	2,047
Present value of net minimum lease payments	20,745
Less: current portion of lease obligations	4,999
Non-current portion of lease obligations	15,746	$ 16,785
ROU assets	20,315	$ 21,390
Finance leases
2021 (excluding the three months ended December 31, 2020)	2,204
2022	3,016
2023	3,098
2024	3,181
2025 and thereafter	28,285
Total minimum lease payments	39,784
Less: amounts representing interest	9,935
Present value of net minimum lease payments	29,849
Less: current portion of lease obligations	1,972
Non-current portion of lease obligations	27,877
ROU assets	$ 25,674
Location of operating lease liabilities included on Consolidated Balance Sheets	us-gaap:OtherAccruedLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent
Location of finance lease liabilities included on Consolidated Balance Sheets	us-gaap:OtherAccruedLiabilitiesCurrent us-gaap:OtherLiabilitiesNoncurrent
Location of operating lease ROU assets included on Consolidated Balance Sheets	us-gaap:OperatingLeaseRightOfUseAsset
Location of finance lease ROU assets included on Consolidated Balance Sheets	us-gaap:PropertyPlantAndEquipmentNet