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Share-based Payments Arrangement - CHTSC's Outstanding Stock Options (Detail) - CHT Security Co., Ltd. (CHTSC) [Member] | 12 Months Ended
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Dec. 31, 2020 $ / shares | Dec. 31, 2019 $ / shares
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Number of options, Options outstanding at beginning of the year | 4,500 |
Number of options, Options outstanding at end of the year | 4,328 | 4,500
Number of options, Options exercisable at end of the year | 1,082 | 0
Weighted-average exercise price, Options outstanding at beginning of the year | $ 19.085 |
Weighted-average exercise price, Options outstanding at end of the year | 19.085 | $ 19.085
Weighted average exercise price, Option exercisable at end of the year | $ 19.085 | $ 0
Granted on December 20, 2019 [Member] |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Number of options, Options outstanding at beginning of the year | 4,500 | 0
Number of options, Options granted | 0 | 4,500
Number of options, Options forfeited | (172) | 0
Number of options, Options outstanding at end of the year | 4,328 | 4,500
Number of options, Options exercisable at end of the year | 1,082 | 0
Weighted-average exercise price, Options outstanding at beginning of the year | $ 19.085 | $ 0
Weighted average exercise price, Options granted | 0 | 19.085
Weighted-average exercise price, Options forfeited | 0 | 0
Weighted-average exercise price, Options outstanding at end of the year | 19.085 | 19.085
Weighted average exercise price, Option exercisable at end of the year | $ 19.085 | $ 0

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- Definition The number of share options outstanding in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph d -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_d&doctype=Standard -URIDate 2020-01-01 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause i -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_i&doctype=Standard -URIDate 2020-01-01 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2020-01-01 -Paragraph 45 -Subparagraph b -Clause vi -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IFRS&num=2&code=ifrs-tx-2020-en-r&anchor=para_45_b_vi&doctype=Standard -URIDate 2020-01-01 + Details
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