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Stock-Based Compensation - Summary of Changes in Nonvested Restricted Stock Awards (Detail) - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]      
Nonvested at beginning of period, Shares 84,600    
Granted, Shares 52,750 48,300 35,400
Vested, Shares (36,624)    
Nonvested at end of period, Shares 100,726 84,600  
Nonvested at beginning of period, Weighted-average Grant Date Fair Value $ 17.01    
Granted, Weighted-average Grant Date Fair Value 17.66    
Vested, Weighted-average Grant Date Fair Value 16.96    
Nonvested at end of period, Weighted-average Grant Date Fair Value $ 17.36 $ 17.01