Leases - Schedule of Financial Statement Classification of Lease Balances Within Condensed Consolidated Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Sep. 30, 2020
Leases [Abstract]
Operating lease assets	$ 5,155	$ 5,124
Finance lease assets	$ 23	$ 26
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	us-gaap:PropertyPlantAndEquipmentNet	us-gaap:PropertyPlantAndEquipmentNet
Total lease assets	$ 5,178	$ 5,150
Operating lease liabilities	$ 131	$ 113
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Finance lease liabilities	$ 10	$ 11
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent	us-gaap:AccruedLiabilitiesCurrent
Operating lease liabilities	$ 5,077	$ 5,048
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	asys:FinanceAndOperatingLeaseLiabilityNoncurrent	asys:FinanceAndOperatingLeaseLiabilityNoncurrent
Finance lease liabilities	$ 13	$ 16
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	asys:FinanceAndOperatingLeaseLiabilityNoncurrent	asys:FinanceAndOperatingLeaseLiabilityNoncurrent
Total lease liabilities	$ 5,231	$ 5,188