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Share-based Payments - Summary of Changes in the Number of Stock Options and the Weighted-Average Exercise Price (Detail) | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2016
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Beginning | 318,506 | 263,123
Granted | 316,949 | 373,419
Expired | 193,094 | 181,685
Forfeited | 0 | 0
Exercised | 125,412 | 136,351
Ending | 316,949 | 318,506
Number of shares exercisable | 0 | 0
9th Grant [member] |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Beginning |  | 263,123
Granted |  | 54,913
Expired |  | 181,685
Forfeited |  | 0
Exercised |  | 136,351
Number of shares exercisable |  | 0
10th Grant [member] |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Beginning | 318,506 |
Granted |  | 318,506
Expired | 193,094 |
Forfeited | 0 | 0
Exercised | 125,412 |
Ending |  | 318,506
Number of shares exercisable | 0 | 0
11th grant [member] |  |
Disclosure of terms and conditions of share-based payment arrangement [Line Items] |  |
Granted | 316,949 |
Forfeited | 0 |
Ending | 316,949 |
Number of shares exercisable | 0 |

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- Definition The number of share options exercisable in a share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IFRS -Number 2 -IssueDate 2017-01-01 -Paragraph 45 -Subparagraph b -Clause vii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IFRS&num=2&date=2017-03-01&anchor=para_45_b_vii&doctype=Standard -URIDate 2017-03-09 + Details
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