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Stockholders' Equity - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Par value of common stock repurchased $ 0.01 $ 0.01  
Common stock reserved for issuance 1,500,000    
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant 477,129    
Total unrecognized compensation cost related to nonvested shares of common stock granted $ 11.9    
Weighted average period of cost recognized 3 years 1 month 29 days    
Total fair value of shares of common stock vested $ 4.5 $ 4.1 $ 3.9
Compensation expense related to nonvested stock grants $ 4.9 $ 4.2 $ 4.1
Price of shares issued under Employee Stock Purchase Plan as a percentage of FMV 95.00%    
Number of shares reserved for the Employee Stock Purchase Plan 250,000    
Shares authorized for issuance under Employee Stock Purchase Plan 250,000    
Shares redeemed to satisfy personal tax obligations 52,119 42,197 40,716
Employee [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of non-vested shares 5 years    
Nonvested stock grants to employees 220,800 182,865 172,545
Director [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of non-vested shares 1 year    
Non vested stock grants to Independent director 15,300 16,200 26,900
New Director [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Vesting period of non-vested shares 3 years