ACQUISITIONS (Details) - Acquisition of CornellCookson, Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018	Jun. 04, 2018
Business Acquisition [Line Items]
Goodwill	$ 442,643	$ 437,067	$ 439,395
CornellCookson
Business Acquisition [Line Items]
Accounts receivable				$ 30,400
Inventories				12,336
Property, plant and equipment				49,426
Goodwill				43,183
Intangible assets				67,600
Other current and non-current assets				2,648
Total assets acquired				205,593
Accounts payable and accrued liabilities				12,507
Long-term liabilities				660
Total liabilities assumed				13,167
Total				192,426
Receivables gross				30,818
Allowance for accounts receivable				418
Inventory, gross				13,434
Inventory valuation reserves				$ 1,098