Property, Plant, and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 593,688	$ 536,881
Less: accumulated depreciation	(260,104)	(216,858)
Property, plant and equipment, net	333,584	320,023
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	488,924	399,619
Land and buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	64,165	76,459
Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 40,599	$ 60,803