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Stock-Based Compensation - Restricted Stock - Service-Based - Additional Information (Detail) - Service Based Restricted Stock [Member] - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2017
Mar. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grants vesting period 4 years  
Stock awards issued during the period 285,000  
Restricted shares vested grant date intrinsic value $ 1.0 $ 0.7
Unrecognized compensation expense $ 5.2  
Weighted average period 1 year 7 months 6 days  
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Grants vesting period 2 years