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Stock Incentive Plans - Additional Information (Detail)
$ / shares in Units, $ in Millions
 12 Months Ended
Dec. 31, 2015
USD ($)
Installment
$ / shares
shares
Dec. 31, 2014
Installment
$ / shares
shares
Dec. 31, 2013
Installment
$ / shares
shares
Dec. 31, 2012
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Stock-based awards issued to outside consultants or advisors 0      
Option awards shares outstanding under the 2009 plan together with the 2003 Plan and its predecessor 360,100 367,533 400,399 538,697
Outstanding options expiration period from the date of grant 10 years      
Number of equal annual installments options are exercisable | Installment 4      
Options exercisable period after date of grant 1 year      
Restricted stock units outstanding 150,811      
New grants of stock options 0      
Options granted below market price   0 0  
Number of equal annual installments in which restricted stock units vest | Installment 4 4 4  
Annual installments for vesting of restricted stock beginning from date of grant, period 1 year 1 year 1 year  
Unrecognized compensation expense related to stock options and restricted stock units | $ $ 6.2      
Weighted average period 2 years 8 months 27 days      
Two Thousand And Fifteen Stock Incentive Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of shares of common stock reserved for issuance under the 2015 Plan 1,000,000      
Aggregate number of shares for which incentive stock options may be granted under the Plan 900,000      
Restricted stock units granted 56,425      
2009 Plan [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Option awards shares outstanding under the 2009 plan together with the 2003 Plan and its predecessor 360,100      
Restricted stock units granted 8,000      
Restricted Stock Units [Member]        
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Restricted stock units granted 64,425 69,371 44,970  
Restricted stock units outstanding 150,811 126,846 80,595 47,500
Weighted average grant date fair value of restricted stock units, granted | $ / shares $ 37.79 $ 50.47 $ 50.28