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Share-Based Compensation Plan - Additional Information (Detail)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Maximum number of common shares that can be issued upon exercise of options granted equal to percentage of number of common shares issued and outstanding 10.00%  
Term during which an option may be exercised 10 years  
Options vest at a rate 33.00%  
Description of vesting requirements for share based payment arrangement Options vest at a rate of 33% per year, beginning one year following the grant date of the options.  
Share-based compensation expense $ 1,454 $ 1,519
Performance based restricted stock units [member]    
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Number of instruments other equity instruments granted   21,000
Number of other equity instruments outstanding in share based payment arrangement 1,056,666 128,000
Number of non-vested other equity instruments outstanding in share based payment arrangement 881,333  
Performance based restricted stock units [member] | Exercise price in CA$ 5.79 [member]    
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Number of instruments other equity instruments granted 979,000 885,000