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Tax matters - Tax Cuts and Jobs Act (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Tax matters |  |
Applicable tax rate | 21.00% | 35.00%
Deferred tax credit | $ 31.2 |
One off tax charge | $ 1.7 |

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- Definition Amount of reasonable estimate for income tax benefit for remeasurement of deferred tax liability from change in tax rate pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete. + References No definition available. + Details
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- Definition Amount of reasonable estimate for income tax expense from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act of 2017 for which accounting for tax effect is incomplete. + References No definition available. + Details
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- Definition The applicable income tax rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2018-01-01 -Paragraph 81 -Subparagraph c -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard -URIDate 2018-03-16 + Details
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- References No definition available. + Details
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