v3.8.0.1

Accounting policies (Additional Information) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) ¥ / $	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2015 ¥ / $	Dec. 31, 2015	Dec. 31, 2016 ¥ / $	Dec. 31, 2016
Accounts receivable, trade and other receivables
Net of provision for doubtful accounts	$ 196	$ 196
Revenue recognition
Sales returns	$ 0	$ 0	$ 27
Foreign currency translation
Balance sheet, excluding equity, foreign currency translation	6.53					6.94	1.00
Income and cash flow statement foreign currency translation	6.76	6.64		6.23	1.00

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- Definition

Foreign Currency Exchange Rate Translation Balance Sheet

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- Definition

The average translation rates applied to the income and cash flow statement amounts.

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- Definition

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.4)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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The aggregate refunds recognized during an accounting period due to goods returned by customers (other than under warranty provisions). Returns are a deduction from gross revenue in arriving at net revenue.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1(a))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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