Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets.

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Number of operating segments. An operating segment is a component of an enterprise: (a) that engages in business activities from which it may earn revenues and incur expenses (including revenues and expenses relating to transactions with other components of the same enterprise), (b) whose operating results are regularly reviewed by the enterprise's chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance, and (c) for which discrete financial information is available. An operating segment may engage in business activities for which it has yet to earn revenues, for example, start-up operations may be operating segments before earning revenues.

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The net result for the period of deducting operating expenses from operating revenues.

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The cash outflow associated with the acquisition of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale; includes cash outflows to pay for construction of self-constructed assets.

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Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Business Segments (Details) $ in Thousands	3 Months Ended								12 Months Ended
Business Segments (Details) $ in Thousands	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)	Jun. 30, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2018 USD ($) segment	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Segment Reporting Information [Line Items]
Revenues									$ 176,426	$ 164,516	$ 120,308
Number of operating segments \| segment									3
Operating loss	$ (8,848)	$ 2,936	$ 65	$ 7,766	$ 8,034	$ 3,971	$ (1,400)	$ (180)	$ 1,919	10,425	(7,908)
Capital expenditures									1,495	1,256	978
Depreciation and amortization									1,854	2,493	2,974
Identifiable assets	149,406				191,623				149,406	191,623
Solar
Segment Reporting Information [Line Items]
Capital expenditures									540	1,008	235
Depreciation and amortization									1,003	1,544	2,014
Semiconductor
Segment Reporting Information [Line Items]
Capital expenditures									352	236	692
Depreciation and amortization									715	876	870
Polishing
Segment Reporting Information [Line Items]
Capital expenditures									603	12	51
Depreciation and amortization									$ 136	73	90
Product Concentration Risk \| Sales Revenue, Product Line \| Semiconductor
Segment Reporting Information [Line Items]
Concentration risk, percentage									25.00%
Operating Segments \| Solar
Segment Reporting Information [Line Items]
Revenues									$ 82,502	87,031	60,946
Operating loss									(7,050)	6,060	(6,696)
Identifiable assets	48,898				97,999				48,898	97,999
Operating Segments \| Semiconductor
Segment Reporting Information [Line Items]
Revenues									80,163	67,237	50,637
Operating loss									11,848	9,538	3,904
Identifiable assets	59,744				57,177				59,744	57,177
Operating Segments \| Polishing
Segment Reporting Information [Line Items]
Revenues									13,761	10,248	8,725
Operating loss									3,672	2,617	1,588
Identifiable assets	6,545				5,078				6,545	5,078
Corporate, Non-Segment
Segment Reporting Information [Line Items]
Operating loss									(6,551)	(7,790)	$ (6,704)
Identifiable assets	$ 34,219				$ 31,369				$ 34,219	$ 31,369