LEASES - Summary of supplemental balance sheet information (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Operating Leases:
Operating right-of-use assets	$ 144,598	$ 154,349
Lease Liabilities:
Current portion of operating lease liabilities	29,881	29,672
Long-term operating lease liabilities	119,315	130,588
Total operating lease liabilities	149,196	160,260
Finance Leases:
Property, plant and equipment, net	$ 16,466	$ 18,774
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	PROPERTY, PLANT AND EQUIPMENT, net	PROPERTY, PLANT AND EQUIPMENT, net
Lease Liabilities:
Notes payable and current portion of long-term debt	$ 2,347	$ 3,352
Long-term debt, net	14,120	15,339
Total financing lease liabilities	$ 16,467	$ 18,691
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Notes payable and current portion of long-term debt	Notes payable and current portion of long-term debt
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt	Long-term debt
Accumulated depreciation	$ 6,136	$ 2,383