XML 118 R98.htm IDEA: XBRL DOCUMENT v3.8.0.1
Stock-based compensation - Performance and deferred stock unit plan (Details)
12 Months Ended
Jul. 01, 2014
Dec. 31, 2017
CAD
CAD / shares
shares
Dec. 31, 2016
CAD
CAD / shares
shares
Performance restricted share units (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Beginning balance (in shares)   739,300 423,592
Granted/issued (in shares)   248,824 343,706
Forfeited (in shares)   (21,542) (27,998)
Vested/redeemed (in shares)     (69,949)
Ending balance (in shares)   896,633 739,300
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value, Amount Per Share [Abstract]      
Outstanding, beginning of period (CAD per unit) | CAD / shares   CAD 4.84 CAD 4.86
Granted, Weighted average exercise price (CAD per unit) | CAD / shares   5.98 4.97
Vested, Weighted average exercise price (CAD per unit) | CAD / shares   8.57  
Forfeited, Weighted average exercise price (CAD per unit) | CAD / shares   4.05 4.52
Outstanding, end of period (CAD per unit) | CAD / shares   CAD 4.81 CAD 4.84
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Risk-free interest rate   1.17% 0.52%
Expected volatility   46.47% 43.30%
Settlement ratio, per PSU (in shares)   1.34 0
Performance restricted share unit plan | Performance restricted share units (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Award vesting period 3 years    
July 2014 grant | Performance restricted share units (PSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value, Amount Per Share [Abstract]      
Total unrecognized compensation costs related to non-vested non-option share-based payment arrangements | CAD   CAD 2,250,000 CAD 1,878,000
Period for award recognition   1 year 4 months 9 days 1 year 9 months
Deferred share unit plan | Deferred stock units (DSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Annual fixed remuneration   50.00%  
Liability classified deferred stock unit plan | Deferred stock units (DSUs)      
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Beginning balance (in shares)   941,937 928,874
Granted/issued (in shares)   114,895 171,980
Vested/redeemed (in shares)   (65,249) (158,917)
Ending balance (in shares)   991,583 941,937
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Intrinsic Value, Amount Per Share [Abstract]      
Total unrecognized compensation costs related to non-vested non-option share-based payment arrangements | CAD   CAD 0  
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Fair market value (CAD per share) | CAD / shares   CAD 5.72 CAD 5.25
Award units settled during the period | CAD   CAD 343,000 CAD 488,000
Liability classified deferred stock unit plan | Deferred stock units (DSUs) | Accrued liabilities      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Current portion of award obligation | CAD   0 0
Liability classified deferred stock unit plan | Deferred stock units (DSUs) | Other liabilities      
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]      
Non-current portion of award obligation | CAD   CAD 5,672,000 CAD 4,945,000