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Share-based compensation - Summary of Weighted Average Assumptions of Options Granted (Detail) | 9 Months Ended
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Sep. 30, 2020 Years $ / shares | Sep. 30, 2019 Years $ / shares
Disclosure of terms and conditions of share-based payment arrangement [abstract] |  |
Average fair value of options granted (per option) | $ / shares | $ 0.29 |
Expected life of options (years) | Years | 2.2 |
Expected forfeiture rate | 1.00% |

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- Definition The option life of share options granted. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_47_a_i&doctype=Standard -URIDate 2020-01-01 + Details
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Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | ifrs-full_
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Balance Type: | na
Period Type: | duration

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- Definition The weighted average share price used as input to the option pricing model to calculate the fair value of share options granted. [Refer: Option pricing model [member]; Weighted average [member]] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 47 -Subparagraph a -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_47_a_i&doctype=Standard -URIDate 2020-01-01 + Details
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Namespace Prefix: | ifrs-full_
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Balance Type: | na
Period Type: | duration

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- Definition Expected rate of forfeiture share options granted. + References No definition available. + Details
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Period Type: | duration