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Shares - Share Purchase Program (Details) - CAD CAD in Thousands |  |  | 1 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Aug. 14, 2015 | Dec. 18, 2014 | Jun. 30, 2015 | Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Retired through share purchase programs (shares) |  |  |  | 1,803,715 | 500,000 | 1,800,000
Stock Purchase Program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Shares retired during period (shares) |  |  |  |  | 500,000 |
Common stock | NCIB stock purchase program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Retired through share purchase programs (shares) | 532,520 |  |  |  |  |
Shares retired during period (shares) |  |  |  | 532,520 |  |
Increase (decrease) as a result of the retirement of shares |  |  |  | CAD 4,500 |  |
Common stock | Stock Purchase Program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Retired through share purchase programs (shares) |  | 1,771,195 |  |  |  |
Shares retired during period (shares) |  |  | 1,271,195 | 1,771,195 |  |
Increase (decrease) as a result of the retirement of shares |  |  | CAD (10,917) |  | CAD (4,238) |
Percentage of issued and outstanding common shares purchased under Purchase Program |  | 5.00% |  |  |  |
Additional paid in capital | NCIB stock purchase program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Increase (decrease) as a result of the retirement of shares |  |  |  | CAD 2,948 |  |
Additional paid in capital | Stock Purchase Program |  |  |  |  |  |
Equity, Class of Treasury Stock [Line Items] |  |  |  |  |  |
Increase (decrease) as a result of the retirement of shares |  |  | CAD 6,284 |  | CAD 2,297 |

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- Definition Number of shares that have been repurchased and retired during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
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