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Stock-based compensation - Share options plan (Details) $ in Thousands | 12 Months Ended
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Dec. 31, 2020 CAD ($) shares | Dec. 31, 2020 $ / shares shares | Dec. 31, 2019 CAD ($) shares | Dec. 31, 2019 $ / shares
Number of options |  |  |  |
Exercised (in shares)) | (109,100) |  | (327,000) |
Forfeited or expired (in shares) | (4,500) |  |  |
Weighted average exercise price $ per share |  |  |  |
Forfeited or expired (CAD per share) | $ / shares |  | $ 10.13 |  |
Proceeds from options exercised | $ | $ 537 |  | $ 1,953 |
Share option plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Expiration period | 10 years |  |  |
Vesting percentage | 20.00% |  |  |
Number of shares authorized for issuance (in shares) | 2,382,019,000 | 2,382,019,000 |  |
Number of options |  |  |  |
Beginning balance (in shares) | 238,600 |  | 565,600 |
Exercised (in shares)) | (109,100) |  | (327,000) |
Ending balance (in shares) | 125,000 |  | 238,600 |
Weighted average exercise price $ per share |  |  |  |
Beginning balance (CAD per share) | $ / shares |  |  |  | $ 5.40
Exercised (CAD per share) | $ / shares |  | $ 4.91 |  | $ 5.97
Ending balance (CAD per share) | $ / shares |  | $ 4.16 |  |
Proceeds from options exercised | $ | $ 537 |  | $ 1,953 |
Total intrinsic value of options exercised | $ | $ 535 |  | $ 3,274 |

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- Definition Number of shares authorized for issuance under share-based payment arrangement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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