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Share-based Payment Arrangements - Summary of USIE Option Plans Outstanding Share Options (Detail) - USIE option plans [member] | Dec. 31, 2017 USD ($) yr | Dec. 31, 2016 USD ($) yr
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First share options exercise price [member] |  |
Disclosure of range of exercise prices of outstanding share options [Line Items] |  |
Range of Exercise Price Per Share | $ 1.5 | $ 1.5
Weighted Average Remaining Contractual Life (Years) | yr | 3.0 | 4.0
Second and third share options exercise price [member] |  |
Disclosure of range of exercise prices of outstanding share options [Line Items] |  |
Weighted Average Remaining Contractual Life (Years) | yr | 2.9 | 3.9
Second and third share options exercise price [member] | Bottom of range [member] |  |
Disclosure of range of exercise prices of outstanding share options [Line Items] |  |
Range of Exercise Price Per Share | $ 2.4 | $ 2.4
Second and third share options exercise price [member] | Top of range [member] |  |
Disclosure of range of exercise prices of outstanding share options [Line Items] |  |
Range of Exercise Price Per Share | $ 2.9 | $ 2.9

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- Definition Line items represent concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes of the table. + References No definition available. + Details
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- Definition The exercise price of outstanding share options. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2017-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_d&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The weighted average remaining contractual life of outstanding share options. [Refer: Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2017-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_d&doctype=Standard -URIDate 2017-03-09 + Details
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