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Stock-based compensation (Tables) | 12 Months Ended
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Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Schedule of stock-based compensation expenses included in general and administrative expenses | Stock-based compensation expenses included in general and administrative expenses are as follows:
Year ended December 31, |  | 2018 |  |  | 2017 |
Share option plan (note 22(b)) |  | $ | 97 |  |  | $ | 326 |
Equity classified restricted share unit plan (note 22(c)) |  | 2,110 |  |  | 1,293 |
Equity performance restricted share unit plan (note 22(d)) |  | 1,910 |  |  | 1,306 |
Liability classified deferred stock unit plan (note 22(e)) |  | 7,415 |  |  | 1,070 |
|  | $ | 11,532 |  |  | $ | 3,995 |
Schedule of stock options activity |
|  | Number of options |  |  | Weighted average exercise price $ per share |
Outstanding at December 31, 2016 |  | 1,176,080 |  |  | 5.56 |
Exercised(i) |  | (176,800 | ) |  | 3.26 |
Forfeited or expired |  | (85,740 | ) |  | 12.36 |
Outstanding at December 31, 2017 |  | 913,540 |  |  | 5.36 |
Exercised(i) |  | (297,940 | ) |  | 3.43 |
Forfeited or expired |  | (50,000 | ) |  | 16.46 |
Outstanding at December 31, 2018 |  | 565,600 |  |  | 5.40 |
(i) All stock options exercised resulted in new common shares being issued (note 18(a)).
Summary of information about stock options outstanding | The following table summarizes information about stock options outstanding at December 31, 2018:
|  | Options outstanding |  |  | Options exercisable |
Exercise price |  | Number |  |  | Weighted average remaining life |  | Weighted average exercise price |  |  | Number |  |  | Weighted average remaining life |  | Weighted average exercise price |
$2.75 |  | 90,100 |  |  | 3.7 years |  | $ | 2.75 |  |  | 90,100 |  |  | 3.7 years |  | $ | 2.75 |
$2.79 |  | 162,000 |  |  | 3.5 years |  | $ | 2.79 |  |  | 162,000 |  |  | 3.5 years |  | $ | 2.79 |
$5.91 |  | 123,680 |  |  | 5.0 years |  | $ | 5.91 |  |  | 123,680 |  |  | 5.0 years |  | $ | 5.91 |
$6.56 |  | 54,880 |  |  | 2.9 years |  | $ | 6.56 |  |  | 54,880 |  |  | 2.9 years |  | $ | 6.56 |
$8.28 |  | 10,000 |  |  | 0.5 years |  | $ | 8.28 |  |  | 10,000 |  |  | 0.5 years |  | $ | 8.28 |
$8.58 |  | 30,000 |  |  | 1.7 years |  | $ | 8.58 |  |  | 30,000 |  |  | 1.7 years |  | $ | 8.58 |
$9.33 |  | 48,680 |  |  | 1.1 years |  | $ | 9.33 |  |  | 48,680 |  |  | 1.1 years |  | $ | 9.33 |
$10.13 |  | 46,260 |  |  | 2.0 years |  | $ | 10.13 |  |  | 46,260 |  |  | 2.0 years |  | $ | 10.13 |
|  | 565,600 |  |  | 3.3 years |  | $ | 5.40 |  |  | 565,600 |  |  | 3.3 years |  | $ | 5.40 |
Schedule of performance restricted share units |
|  | Number of units |  | Weighted average exercise price $ per share
Outstanding at December 31, 2016 |  | 739,300 |  |  | 4.84 |
Granted |  | 248,824 |  |  | 5.98 |
Vested |  | (69,949 | ) |  | 8.57 |
Forfeited |  | (21,542 | ) |  | 4.05 |
Outstanding at December 31, 2017 |  | 896,633 |  |  | 4.81 |
Granted |  | 197,763 |  |  | 8.01 |
Vested |  | (353,279 | ) |  | 4.27 |
Outstanding at December 31, 2018 |  | 741,117 |  |  | 5.92 |
Schedule of assumptions used in estimate of fair value | The Company estimated the fair value of the PSUs granted during the years ended December 31, 2018 and 2017 using a Monte Carlo simulation with the following assumptions:
|  | 2018 |  |  | 2017 |
Risk-free interest rate |  | 1.98 | % |  | 1.17 | %
Expected volatility |  | 45.04 | % |  | 46.47 | %
Schedule of stock plan activity |
|  | Number of units |
Outstanding at December 31, 2016 |  | 941,937 |
Granted |  | 114,895 |
Redeemed |  | (65,249 | )
Outstanding at December 31, 2017 |  | 991,583 |
Granted |  | 134,656 |
Outstanding at December 31, 2018 |  | 1,126,239 |
Equity classified restricted share unit plan |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Schedule of restricted share unit plan activity |
|  | Number of units |  |  | Weighted average exercise price $ per share |
Outstanding at December 31, 2016 |  | 1,123,975 |  |  | 4.20 |
Granted |  | 355,292 |  |  | 6.02 |
Vested |  | (259,860 | ) |  | 6.24 |
Forfeited |  | (29,474 | ) |  | 4.00 |
Outstanding at December 31, 2017 |  | 1,189,933 |  |  | 4.22 |
Granted |  | 266,196 |  |  | 8.02 |
Vested |  | (487,376 | ) |  | 3.01 |
Forfeited |  | (20,660 | ) |  | 5.45 |
Outstanding at December 31, 2018 |  | 948,093 |  |  | 8.98 |

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- Definition Tabular disclosure for share-based compensation plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + 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 (e) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure of option exercise prices, by grouped ranges, including the upper and lower limits of the price range, the number of shares under option, weighted average exercise price and remaining contractual option terms. + 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 -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure for stock option plans. Includes, but is not limited to, outstanding awards at beginning and end of year, grants, exercises, forfeitures, and weighted-average grant date fair value. + 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 (d) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 Reference 3: 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) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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- Definition Tabular disclosure of the significant assumptions used during the year to estimate the fair value of stock options, including, but not limited to: (a) expected term of share options and similar instruments, (b) expected volatility of the entity's shares, (c) expected dividends, (d) risk-free rate(s), and (e) discount for post-vesting restrictions. + 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 (f)(2) -URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901 + Details
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