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Earnings Per Share (EPS) - Schedule of Reconciliation of Weighted Average Shares Used in the Diluted EPS (Detail) - shares
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Earnings Per Share [Line Items]      
Weighted average common shares-basic 18,117,405 18,144,019 18,795,194
Effect of diluted securities:      
Weighted average common shares-diluted 18,498,745 18,463,161 18,795,194
Stock Options And Employee Stock Purchase Plan [Member]      
Effect of diluted securities:      
Effect of diluted securities 209,691 161,092  
Time-Based Restricted Stock Awards [Member]      
Effect of diluted securities:      
Effect of diluted securities 123,592 138,291  
Performance-based Restricted Stock Awards [Member]      
Effect of diluted securities:      
Effect of diluted securities 48,057 19,759