Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2017	Sep. 30, 2016
Goodwill [Line Items]
Goodwill	$ 12,753	$ 12,388
Accumulated impairment losses	(1,348)	(1,269)
Goodwill [Roll Forward]
Carrying value	11,119
Net exchange differences	286
Carrying value	11,405
Solar
Goodwill [Line Items]
Goodwill	6,962	6,597
Accumulated impairment losses	(1,348)	(1,269)
Goodwill [Roll Forward]
Carrying value	5,328
Net exchange differences	286
Carrying value	5,614
Semiconductor
Goodwill [Line Items]
Goodwill	5,063	5,063
Accumulated impairment losses	0	0
Goodwill [Roll Forward]
Carrying value	5,063
Net exchange differences	0
Carrying value	5,063
Polishing
Goodwill [Line Items]
Goodwill	728	728
Accumulated impairment losses	0	$ 0
Goodwill [Roll Forward]
Carrying value	728
Net exchange differences	0
Carrying value	$ 728

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=35741047&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13770-109266

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

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- Definition

Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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- Definition

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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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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