Accounts Receivable - Movement in the allowance for credit losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ (4,824)	$ (4,057)	$ (4,906)
Charged to costs and expenses	(1,997)	(1,733)	(537)
Write-offs	473	780	1,277
Foreign currency and other	(540)	186	109
Balance at end of period	$ (6,888)	$ (4,824)	$ (4,057)