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Employee Benefit Plans - Additional Information (Detail) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]      
Accumulated other comprehensive loss, expected to be recognized over the next fiscal year $ 161    
Percentage of expected return on plan assets 7.90%    
Percentage of discretionary contributions towards 401(k) Plan, maximum 4.00%    
Company's contribution to the 401(k) Plan $ 2,709 $ 2,383 $ 1,907
Contribution to various defined contribution plans $ 7,115 $ 6,306 $ 5,753