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Retirement plans - Additional information (Details) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2017 USD ($) year | Dec. 31, 2016 USD ($)
Disclosure of net defined benefit liability (asset) [line items] |  |
Retirement obligation (asset) | $ 18,402 | $ 16,541
Weighted average duration of defined benefit obligation | year | 10 |
Unfunded | Foreign | Chile |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Retirement obligation (asset) | $ 25,100 | 22,400
Estimate of contributions expected to be paid to plan for 2018 | 5,100 |
Funded | Domestic |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Retirement obligation (asset) | (6,600) | (5,700)
Estimate of contributions expected to be paid to plan for 2018 | 600 |
Funded | Foreign | Europe |  |
Disclosure of net defined benefit liability (asset) [line items] |  |
Retirement obligation (asset) | $ (100) | $ (200)

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- Definition The estimate of the expected contributions to be made to a defined benefit plan for the next annual reporting period. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 147 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_147_b&doctype=Standard -URIDate 2017-03-09 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 148 -Subparagraph d -Clause iii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_148_d_iii&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The amount of deficit or surplus in a defined benefit plan, adjusted for any effect of limiting a net defined benefit asset to the asset ceiling. [Refer: Defined benefit plans [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 140 -Subparagraph a -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_140_a&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The weighted average duration of a defined benefit obligation. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 19 -IssueDate 2017-01-01 -Paragraph 147 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_147_c&doctype=Standard -URIDate 2017-03-09 + Details
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