LEASES - Summary of Supplemental Balance Sheet Information (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Operating Leases:
Operating right-of-use assets	$ 157,860	$ 161,627
Lease Liabilities:
Current portion of operating lease liabilities	31,304	31,848
Long-term operating lease liabilities	132,634	136,054
Total operating lease liabilities	163,938	167,902
Finance Leases:
Property, plant and equipment, net	$ 17,975	18,774
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization
Lease Liabilities:
Lease liabilities, notes payable and current portion of long-term debt	$ 3,146	3,352
Lease liabilities, long-term debt, net	14,885	15,339
Total financing lease liabilities	$ 18,031	$ 18,691
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtCurrent
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:LongTermDebtNoncurrent
Accumulated depreciation	$ 3,319