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Common Stock and Stock-Based Compensation Plans - Additional Information (Detail)
$ in Thousands
9 Months Ended
Sep. 30, 2017
USD ($)
2011 Stock Incentive Plan  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options and stock appreciation rights granted under stock incentive plans vesting rate, year one 25.00%
Remaining shares vesting period 36 months
Maximum  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Shares vesting period 4 years
Stock Appreciation Rights (SARs) | Maximum  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options granted percentage 400.00%
Restricted Stock Units (RSUs)  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Unrecognized compensation expense $ 12,126
Unrecognized compensation expense, weighted-average period of recognition 1 year 6 months
Employees and non-employees award vesting, description RSUs granted to employees generally vest in three equal annual installments starting on the first anniversary of the grant date. RSUs granted to non-employee directors generally vest in full on the first anniversary of the grant date.
Stock Options, SARs  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Unrecognized compensation expense $ 750
Unrecognized compensation expense, weighted-average period of recognition 1 year 4 months 24 days
Non Employee Director  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Options granted under stock incentive plan vesting rate, each anniversary 25.00%
Employee | Restricted Stock Units (RSUs)  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Shares vesting period 3 years
Non-Employee | Restricted Stock Units (RSUs)  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Shares vesting period 1 year