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Equity - Share options, fair value assumptions (Details) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017
Share-Based Payment Arrangements [Abstract] |  |
Expected life (years) | 4 years | 4 years
Expected volatility | 64.00% | 70.00%
Risk-free interest rate | 2.00% | 1.00%

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- Definition Option life, share options granted, Period + References No definition available. + Details
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- Definition Share-Based Payment Arrangements [Abstract] + References No definition available. + Details
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- Definition The expected volatility of the share price used to calculate the fair value of the share options granted. Expected volatility is a measure of the amount by which a price is expected to fluctuate during a period. The measure of volatility used in option pricing models is the annualised standard deviation of the continuously compounded rates of return on the share over a period of time. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2017-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2017-03-09 + Details
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- Definition The implied yield currently available on zero-coupon government issues of the country in whose currency the exercise price for share options granted is expressed, with a remaining term equal to the expected term of the option being valued (based on the option's remaining contractual life and taking into account the effects of expected early exercise). [Refer: Government [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2017-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_47_a_i&doctype=Standard -URIDate 2017-03-09 + Details
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