PROPERTY, PLANT AND EQUIPMENT - Schedule of Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Sep. 30, 2024
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 1,143,125	$ 1,147,023
Accumulated depreciation	(548,859)	(494,930)
Property, plant and equipment, net	594,266	652,093
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	29,766	29,401
Buildings and related improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	217,894	192,569
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	701,220	596,748
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	22,116	22,814
Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	64,371	57,363
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, at cost	$ 107,758	$ 248,128