Segment and Geographic Information - Long-Lived Assets, Consisting of Property, Plant and Equipment by Geographic Area (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Sep. 30, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 100,669	$ 59,988
North America
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	72,401	50,614
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	72,300	50,500
Asia/Pacific/Other
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	15,628	492
United Kingdom
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	5,019	5,494
Rest of Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Property, plant and equipment, net	$ 7,621	$ 3,388