LEASES - Effect of the Change in Accounting Policy (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Oct. 01, 2019	Sep. 30, 2019
Other Noncurrent Assets:
Operating lease right-of-use asset	$ 47,534	$ 56,071	$ 0
Current Liabilities:
Accrued liabilities	11,792	16,277
Noncurrent Liabilities:
Other	$ 35,713	39,794
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:OtherAssetsNoncurrent
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	us-gaap:OtherLiabilitiesNoncurrent
Adjustments
Other Noncurrent Assets:
Operating lease right-of-use asset		56,071
Current Liabilities:
Accrued liabilities		16,277
Noncurrent Liabilities:
Other		$ 39,794