Accounts Receivable - Allowance for Credit Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 227	$ 148	$ 548
Provision adjustment - expense, net of recoveries	90	188	62
Write-offs and other deductions	(57)	(109)	(462)
Balance at end of period	$ 260	$ 227	$ 148