Segment Information - Schedule of Revenues from External Customers by Geographical Areas (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2021 USD ($) segments	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)
Revenues from External Customers and Long-Lived Assets [Line Items]
Reportable segments | segments	1
Revenues	$ 470,559	$ 518,499	$ 517,180
United States
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	351,422	397,983	406,609
Canada
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	68,655	66,064	64,326
Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	26,615	18,162	18,420
Asia/Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	8,889	18,079	11,405
Europe
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	13,027	15,866	13,746
Mexico, Central and South America
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 1,951	$ 2,345	$ 2,674