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Income Tax - Additional Information (Detail) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 24.10% | 31.90% | 24.90%
United States [member] |  |  |
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 26.00% | 40.00% | 40.00%
France [member] |  |  |
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 34.43% | 39.20% | 34.43%
Germany [member] |  |  |
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 29.00% | 29.00% | 29.00%
Netherlands [member] |  |  |
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 25.00% | 25.00% | 25.00%
Czech Republic [member] |  |  |
Disclosure of income tax expense [line Items] |  |  |
Statutory income tax rate | 19.00% | 19.00% | 19.00%

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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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