PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	$ 376,607	$ 359,486
Less: accumulated depreciation and amortization of assets under capital leases	(265,204)	(253,125)
Net property, plant and equipment	111,403	106,361	$ 106,496
Depreciation expense, including amortization of assets recorded under capital leases	17,255	17,195	16,915
Impairment expense		860
Gain on sale of surplus research and develpoment equipment	(91)	1,820	$ (103)
Land [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	17,525	17,823
Buildings [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	103,601	104,057
Machinery and Equipment [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	195,434	187,649
Furniture and Fixtures [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	7,575	6,770
Information Systems [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	34,271	32,748
Capital Leases [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	1,200	0
Construction in Progress [Member]
Property, Plant and Equipment, Net [Abstract]
Total property, plant and equipment	$ 17,001	$ 10,439

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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The amount of expense recognized in the current period that reflects the allocation of the cost of tangible assets over the assets' useful lives. Includes production and non-production related depreciation.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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Amount before accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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Amount after accumulated depreciation, depletion and amortization of physical assets used in the normal conduct of business to produce goods and services and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, and furniture and fixtures.

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