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Significant accounting policies - Stock-based Compensation (Details) (Restricted Share Unit (RSU)) | 12 Months Ended
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Dec. 31, 2014
Restricted Share Unit (RSU) |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |
Award service period | 2 years
Award vesting period | 3 years
Number of trading days used to determine weighted average trading price of common shares | 5 days
Compensation expense recognition period | 3 years

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- Definition Share-based Compensation Arrangement by Share-based Payment Award, Number of Trading Days Used to Calculate Weighted Average Trading Price of Common Stock + References No definition available. + Details
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- Definition Share-based Compensation Arrangement by Share-based Payment Award, Period for Recognition + References No definition available. + Details
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- Definition Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Details
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