ACQUISITIONS (Details) - Acquisition of CornellCookson, Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 04, 2018	Sep. 30, 2017	Sep. 30, 2016
Business Acquisition [Line Items]
Goodwill	$ 439,395		$ 319,139	$ 306,163
Cornell Cookson [Member]
Business Acquisition [Line Items]
Accounts receivable		$ 30,400
Inventories		12,336
Property, plant and equipment		49,426
Goodwill		42,883
Intangible assets		67,600
Other current and non-current assets		2,648
Total assets acquired		205,293
Accounts payable and accrued liabilities		12,207
Long-term liabilities		660
Total liabilities assumed		12,867
Total		192,426
Receivables gross		30,818
Allowance for accounts receivable		418
Inventory, gross		13,433
Inventory valuation reserves		$ 1,098