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Share-Based Compensation - Additional Information (Detail)
3 Months Ended 6 Months Ended
Jun. 30, 2017
USD ($)
shares
Jun. 30, 2016
USD ($)
Jun. 30, 2017
USD ($)
Deferral
shares
Jun. 30, 2016
USD ($)
shares
Dec. 31, 2016
shares
May 10, 2016
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Deferred shares and held by the rabbi trust 297,840   297,840   297,281  
1999 Stock Option Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercised, Number of Shares     0      
Granted, Number of Shares     0      
Long Term Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards 900,000   900,000      
2016 Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards 100,000   100,000     1,000,000
Incentive plan expiry date     May 10, 2026      
Long Term Incentive Plan Stock Option [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercised, Number of Shares     0 0    
Weighted-average period     2 years      
Granted, Number of Shares     5,000 0    
Expected compensation cost related to unvested awards not yet recognized | $ $ 100,000   $ 100,000      
Long Term Incentive Plan Stock Option [Member] | After One Year [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option awards vesting percentage     50.00%      
Long Term Incentive Plan Stock Option [Member] | After Two Years [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option awards vesting percentage     75.00%      
Long Term Incentive Plan Stock Option [Member] | After Three Years [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Stock option awards vesting percentage     100.00%      
Long Term Incentive Plan Stock Option [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Compensation expenses | $ $ 100,000 $ 100,000 $ 100,000 $ 100,000    
Deferred Compensation Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Number of deferrals | Deferral     2      
Stock Options [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Exercised, Number of Shares     0 0    
Stock Options [Member] | 1999 Stock Option Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Compensation expenses | $     $ 0 $ 0    
Stock Options [Member] | 2016 Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards           100,000
Restricted Stock Units (RSUs) [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards 800,000   800,000      
Restricted Stock Units (RSUs) [Member] | 2016 Incentive Plan [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards           900,000
Long Term Incentive Stock Option [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Common shares reserved for awards 100,000   100,000      
Long Term Incentive Stock Option [Member] | Minimum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Option issued under plan vest and expire     5 years      
Long Term Incentive Stock Option [Member] | Maximum [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Option issued under plan vest and expire     10 years      
Time-Based RSUs [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Compensation expenses | $ $ 100,000 100,000 $ 200,000 200,000    
Compensation cost expected to be recognized over period | $ 600,000   $ 600,000      
Weighted-average period     2 years 1 month 6 days      
Performance-Based RSUs [Member]            
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]            
Weighted-average period     2 years 1 month 6 days      
Performance-based compensation expense (income) | $ 400,000 $ 100,000 $ 900,000 $ 300,000    
Remaining performance-based compensation expense | $ $ 3,100,000   $ 3,100,000