Restructuring and Other Costs, Net - Schedule of Accrual Activity Relating to Restructuring Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2020			$ 2,702
Restructuring and other costs, net	$ 1,760	$ 3,301	2,777	$ 13,725
Non-cash adjustments			2,749
Cash payments			(3,556)
Foreign exchange impact on ending balance			(39)
Balance at June 30, 2021	4,633		4,633
Personnel
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2020			764
Restructuring and other costs, net		2,452	381	3,133
Cash payments			(719)
Foreign exchange impact on ending balance			6
Balance at June 30, 2021	432		432
Facilities
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2020			10
Restructuring and other costs, net	447		1,012
Non-cash adjustments			2,749
Cash payments			(852)
Foreign exchange impact on ending balance			(45)
Balance at June 30, 2021	2,874		2,874
Restructuring Subtotal
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2020			774
Restructuring and other costs, net	447	2,452	1,393	3,133
Non-cash adjustments			2,749
Cash payments			(1,571)
Foreign exchange impact on ending balance			(39)
Balance at June 30, 2021	3,306		3,306
Other
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2020			1,928
Restructuring and other costs, net	1,313	$ 849	1,384	$ 10,592
Cash payments			(1,985)
Balance at June 30, 2021	$ 1,327		$ 1,327