Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation Plans - 2013 Omnibus Equity Incentive Plan - Additional Information (Detail)

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Stock-Based Compensation Plans - 2013 Omnibus Equity Incentive Plan - Additional Information (Detail) - USD ($)
9 Months Ended 12 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vested shares 288,011    
Tax benefit from stock-based award activity included in additional paid-in capital   $ 157,000 $ 2,700,000
Deferred stock units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Fully vested deferred stock units remaining outstanding 930,419    
2013 Omnibus Equity Incentive Plan [Member] | Restricted Stock Awards [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 3 years    
2013 Omnibus Equity Incentive Plan [Member] | Restricted Stock Units [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period 5 years    
Vested shares 272,093    
Number of common stock shares withheld to pay employee statutory withholding taxes 54,409    
Vested and delivered shares 277,251