Major Customers and Foreign Sales (Details) - Net revenues	12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	100.00%	100.00%	100.00%
Total Americas
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	14.00%	12.00%	20.00%
Total Asia
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	70.00%	75.00%	68.00%
Total Europe
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	16.00%	13.00%	12.00%
Customer Number One
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	25.00%	25.00%	11.00%
Geographic Concentration Risk | United States
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	12.00%	11.00%	17.00%
Geographic Concentration Risk | Other
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	2.00%	1.00%	3.00%
Geographic Concentration Risk | Taiwan
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	7.00%	12.00%	15.00%
Geographic Concentration Risk | Malaysia
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	6.00%	9.00%	18.00%
Geographic Concentration Risk | China
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	53.00%	47.00%	28.00%
Geographic Concentration Risk | Other
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	4.00%	7.00%	7.00%
Geographic Concentration Risk | Germany
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	7.00%	5.00%	3.00%
Geographic Concentration Risk | Other
Revenue, Major Customer [Line Items]
Revenue, major customer, percentage	9.00%	8.00%	9.00%