Property, Plant and Equipment - Schedule (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Sep. 30, 2019
Property, Plant and Equipment [Line Items]
Right-of-use Asset	$ 2,540
Property, plant and equipment, at cost	291,093	$ 251,403
Accumulated amortization	(173,428)	(150,734)
Property, plant and equipment, net	117,665	100,669
Buildings, land, and land use right
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	50,748	50,583
Computer equipment and software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	70,673	61,603
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	97,806	89,481
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	7,578	7,423
Leasehold improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	40,728	30,612
Capital projects in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 21,020	$ 11,701