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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
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

X

- 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.

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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

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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
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-URIDate 2017-03-09

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