Financial instruments (Details 28) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Loans [Member] \| Interest Rate Risk [Member]
Disclosure of financial instruments [Line Items]
Line item in the statement of financial position	Loans	Loans
Carrying amount, assets	$ 0	$ 18,502
Loans [Member] \| Interest Rate Risk [Member] \| Fair value hedges [member]
Disclosure of financial instruments [Line Items]
Thereof accumulated fair value adjustments, assets	$ 0	$ 12
Loans [Member] \| Currency risk [member]
Disclosure of financial instruments [Line Items]
Line item in the statement of financial position	Loans	Loans
Carrying amount, assets	$ 25,027	$ 9,252
Loans [Member] \| Currency risk [member] \| Fair value hedges [member]
Disclosure of financial instruments [Line Items]
Thereof accumulated fair value adjustments, assets	$ 744	$ 706
Issuances [Member] \| Interest Rate Risk [Member]
Disclosure of financial instruments [Line Items]
Line item in the statement of financial position	Short and long term borrowings and debt	Short and long term borrowings and debt
Carrying amount, liabilities	$ 355,000	$ 755,000
Issuances [Member] \| Interest Rate Risk [Member] \| Fair value hedges [member]
Disclosure of financial instruments [Line Items]
Thereof accumulated fair value adjustments, liabilities	$ (4,411)	$ 2,089
Issuances [Member] \| Currency risk [member]
Disclosure of financial instruments [Line Items]
Line item in the statement of financial position	Short and long term borrowings and debt	Short and long term borrowings and debt
Carrying amount, liabilities	$ (249,328)	$ (308,739)
Issuances [Member] \| Currency risk [member] \| Fair value hedges [member]
Disclosure of financial instruments [Line Items]
Thereof accumulated fair value adjustments, liabilities	$ (2,301)	$ (49)
Foreign exchange rate risk and FX [Member] \| Currency risk [member]
Disclosure of financial instruments [Line Items]
Line item in the statement of financial position	Financial instruments at FVOCI	Financial instruments at FVOCI
Carrying amount, assets	$ 12,369	$ 22,188
Foreign exchange rate risk and FX [Member] \| Currency risk [member] \| Fair value hedges [member]
Disclosure of financial instruments [Line Items]
Thereof accumulated fair value adjustments, assets	$ (32)	$ (232)

The accumulated amount of fair value hedge adjustment on a hedged item that is included in the carrying amount of the hedged item, recognised in the statement of financial position as an asset. [Refer: Hedged items [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24B
-Subparagraph a
-Clause ii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_a_ii&doctype=Standard
-URIDate 2017-03-09

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- Definition

+ References

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- Definition

The description of the line item in the statement of financial position that includes the hedged item. [Refer: Hedged items [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24B
-Subparagraph a
-Clause iii
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_a_iii&doctype=Standard
-URIDate 2017-03-09

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- Definition

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+ References

No definition available.

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- Definition

The amount of a hedged item, recognised as an asset. [Refer: Hedged items [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24B
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_a_i&doctype=Standard
-URIDate 2017-03-09

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- Definition

The amount of a hedged item, recognised as a liability. [Refer: Hedged items [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Note Effective 2018-01-01
-Name IFRS
-Number 7
-IssueDate 2017-01-01
-Paragraph 24B
-Subparagraph a
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=7&date=2017-03-01&anchor=para_24B_a_i&doctype=Standard
-URIDate 2017-03-09

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