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Employee Benefit Plan - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Defined Contribution Plan Disclosure [Line Items]      
Employer matching contribution percentage description We make a nondiscretionary matching contribution equal to 100% of the first 3% and 50% of the next 2% of compensation contributed by employees.    
Matching contributions from the employer $ 2,485 $ 2,413 $ 2,196
Employee contribution first 3% [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Nondiscretionary matching contribution 3.00%    
Employer matching contribution percent for employee contribution 100.00%    
Employee contribution next 2% [Member]      
Defined Contribution Plan Disclosure [Line Items]      
Nondiscretionary matching contribution 2.00%    
Employer matching contribution percent for employee contribution 50.00%