Restructuring and Other Costs, Net - Schedule of Accrual Activity Relating to Restructuring Reserves (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2021			$ 5,035
Restructuring and other costs, net	$ 474	$ 537	5,389	$ 1,017
Non-cash adjustments			(4,393)
Cash (payments) receipts			(2,787)
Foreign exchange impact on ending balance			15
Balance at March 31, 2022	3,259		3,259
Personnel
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2021			1,620
Restructuring and other costs, net	13	45	250	381
Cash (payments) receipts			(1,219)
Balance at March 31, 2022	651		651
Facilities
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2021			1,881
Restructuring and other costs, net	170	447	367	565
Non-cash adjustments			(393)
Cash (payments) receipts			(64)
Foreign exchange impact on ending balance			15
Balance at March 31, 2022	1,806		1,806
Restructuring Subtotal
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2021			3,501
Restructuring and other costs, net	183	492	617	946
Non-cash adjustments			(393)
Cash (payments) receipts			(1,283)
Foreign exchange impact on ending balance			15
Balance at March 31, 2022	2,457		2,457
Other
Restructuring Cost And Reserve [Line Items]
Balance at September 30, 2021			1,534
Restructuring and other costs, net	291	$ 45	4,772	$ 71
Non-cash adjustments			(4,000)
Cash (payments) receipts			(1,504)
Balance at March 31, 2022	$ 802		$ 802